Method for disassembling/assembling gas turbine, seal plate assembly, and gas turbine rotor

ABSTRACT

A method for disassembling/assembling a gas turbine including a seal plate disposed on a first side of a rotor disc in an axial direction of the rotor disc, and a seal plate restraint part for restricting movement of the seal plate relative to the rotor disc in a radial direction of the rotor disc includes a seal-plate-restraint-state switching step of moving the seal plate restraint part along the axial direction to switch between a seal plate non-restraint state where the seal plate restraint part does not restrict movement of the seal plate in the radial direction and a seal plate restraint state where at least a part of the seal plate restraint part protrudes in the axial direction from the seal plate and thereby restricts movement of the seal plate in the radial direction.

TECHNICAL FIELD

The present disclosure relates to a method for disassembling/assemblinga gas turbine, a seal plate assembly, and a gas turbine rotor.

BACKGROUND ART

A gas turbine generally includes a gas turbine rotor including a rotordisc, a plurality of blades mounted on an outer peripheral surface ofthe rotor disc, and at least one seal plate assembly for the blades.

The seal plate assembly is disposed on at least one axial side of therotor disc to seal the axial gas flow in a space between blades whichare adjacent in the circumferential direction of the rotor disc.

A gas turbine generally includes a rotor disc, a plurality of bladesmounted on an outer peripheral surface of the rotor disc, and at leastone seal plate assembly for the blades.

Patent Document 1 discloses a gas turbine including a seal plateassembly (locking plate assembly) disposed on axially upstream anddownstream sides of a rotor disc.

In the gas turbine according to Patent Document 1, the upstream sealplate assembly includes a seal plate (locking plate) configured toengage with a blade to restrict movement of the blade in the axialdirection, and a seal plate restraint part (eccentric cam) configured toengage with the rotor disc to restrict movement of the seal plate in theradial direction. The eccentric cam is held to the seal plate whilebeing in contact with the outer peripheral surface of the rotor disc.When the eccentric cam rotates, the position of the rotation center ofthe eccentric cam relative to the outer peripheral surface of the rotordisc changes in accordance with the phase of the eccentric cam, and theseal plate moves in the radial direction of the rotor disc.

When the gas turbine is disassembled or assembled, the eccentric cam isrotated and moved in the radial direction of the rotor disc to switchbetween a state where the seal plate engages with the blade and a statewhere the seal plate does not engage with the blade.

CITATION LIST Patent Literature

Patent Document 1: US Patent Application Publication No. 2006/0073021

SUMMARY Problems to be Solved

As described above, in the seal plate assembly disclosed in PatentDocument 1, the state where the seal plate engages with the blade andthe state where the seal plate does not engage with the blade areswitched by rotation of the eccentric cam.

Thus, there is a risk that, when the eccentric cam rotates by frictioncaused between the outer peripheral surface of the rotor disc and theouter peripheral surface of the eccentric cam due to vibration duringoperation of the gas turbine or due to acceleration or deceleration ofrotation of the rotor disc during operation of the gas turbine, the sealplate moves in the radial direction at an unintended timing, which canrelease the engagement between the seal plate and the blade.

At least one embodiment of the present invention was made in view of theabove typical problem, and an object thereof is to provide a method fordisassembling/assembling a gas turbine, a seal plate assembly, and a gasturbine rotor including the same whereby it is possible to controlswitching between the engagement state and the non-engagement betweenthe seal plate and the blade at an unintended timing.

Solution to the Problems

(1) According to at least one embodiment of the present invention, amethod for disassembling/assembling a gas turbine including a seal platedisposed on a first side of a rotor disc in an axial direction of therotor disc and a seal plate restraint part for restricting movement ofthe seal plate relative to the rotor disc in a radial direction of therotor disc comprises a seal-plate-restraint-state switching step ofmoving the seal plate restraint part along the axial direction to switchbetween a seal plate non-restraint state where the seal plate restraintpart does not restrict movement of the seal plate in the radialdirection and a seal plate restraint state where at least a part of theseal plate restraint part protrudes in the axial direction from the sealplate and thereby restricts movement of the seal plate in the radialdirection.

With the method for disassembling/assembling a gas turbine described inthe above (1), in the seal-plate-restraint-state switching step, theseal plate non-restraint state and the seal plate restraint state areswitched by moving the seal plate restraint part along the axialdirection.

Thus, for instance, even if force acts on the seal plate restraint partin a direction different from the axial direction of the seal platerestraint part by friction caused between the outer peripheral surfaceof the rotor disc and the seal plate restraint part due to vibrationduring operation of the gas turbine, or due to acceleration ordeceleration of rotation of the rotor disc during operation of the gasturbine, the seal plate non-restraint state and the seal plate restraintstate are not easily switched.

Thus, it is possible to control switching between the engagement stateand the non-engagement state between the seal plate and the blade at anunintended timing.

(2) In some embodiments, in the method for disassembling/assembling agas turbine described in the above (1), the first side in the axialdirection is a downstream side of a combustion gas flow in the axialdirection, and the second side in the axial direction is an upstreamside of the combustion gas flow in the axial direction.

With the method for disassembling/assembling a gas turbine described inthe above (2), it is possible to switch between the seal plate restraintstate and the seal plate non-restraint state in the seal plate assemblydisposed downstream of the rotor disc, from the upstream side of therotor disc, while visually recognizing whether the seal plate restraintpart is in the seal plate restraint state or the seal platenon-restraint state, when disassembling or assembling the gas turbine.Thus, it is possible to easily and appropriately switch between the sealplate restraint state and the seal plate non-restraint state of the sealplate assembly disposed downstream of the rotor disc from the upstreamside of the rotor disc.

Consequently, it is easy to appropriately switch between the engagementstate and the non-engagement state between the seal plate and the bladein the seal plate assembly disposed downstream of the rotor disc, fromthe upstream side of the rotor disc, when disassembling or assemblingthe gas turbine.

Further, in a case where a casing of the gas turbine has an opening(e.g., opening for attaching combustor or entrance for operators) on theupstream side of the rotor disc, it is possible to attach or remove theblade with respect to the rotor disc, without removing the casing of thegas turbine, from the upstream side of the rotor disc. Thus, it ispossible to improve maintenance performance of the gas turbine.

(3) In some embodiments, in the method for disassembling/assembling agas turbine described in the above (1) or (2), theseal-plate-restraint-state switching step includes operating the sealplate restraint part through a space between two adjacent blades, on aradially inner side of platforms of the two blades, to switch betweenthe seal plate non-restraint state and the seal plate restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (3), in some cases, a relatively wide space is ensured betweentwo adjacent blades, on the radially inner side of the platforms of thetwo blades, for a reason described later. Thus, it is possible to easilyswitch between the seal plate non-restraint state and the seal platerestraint state by operating the seal plate restraint part through therelatively wide space.

(4) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (3), the rotor discincludes a through hole extending along the axial direction, and theseal-plate-restraint-state switching step includes operating the sealplate restraint part via the through hole to switch between the sealplate non-restraint state and the seal plate restraint state.

(5) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (4), theseal-plate-restraint-state switching step includes switching between astate where the seal plate restraint part does not engage with the rotordisc and a state where the seal plate restraint part engages with therotor disc by moving the seal plate restraint part along the axialdirection to switch between the seal plate non-restraint state and theseal plate restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (5), in the seal-plate-restraint-state switching step, theseal plate non-restraint state and the seal plate restraint state areswitched by moving the seal plate restraint part along the axialdirection.

Thus, for instance, even if force acts on the seal plate restraint partin a direction different from the axial direction of the seal platerestraint part by friction caused between the outer peripheral surfaceof the rotor disc and the seal plate restraint part due to vibrationduring turning of the gas turbine rotor, or due to acceleration ordeceleration of rotation of the rotor disc during turning of the gasturbine rotor, the seal plate non-restraint state and the seal platerestraint state are not easily switched.

Thus, it is possible to control switching between the engagement stateand the non-engagement state between the seal plate and the blade at anunintended timing.

Further, since the seal plate non-restraint state and the seal platerestraint state are switched by switching between the engagement stateand the non-engagement state between the seal plate restraint part andthe rotor disc, it is possible to enhance the effect of controllingswitching between the engagement state and the non-engagement statebetween the seal plate and the blade at an unintended timing.

(6) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (5), theseal-plate-restraint-state switching step includes moving the seal platerestraint part between a position where the seal plate restraint partand the rotor disc do not overlap in the axial direction and a positionwhere the seal plate restraint part and the rotor disc overlap in theaxial direction to switch between the seal plate non-restraint state andthe seal plate restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (6), it is possible to enhance the effect of controllingswitching between the engagement state and the non-engagement statebetween the seal plate and the blade at an unintended timing.

(7) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (6), theseal-plate-restraint-state switching step includes rotating the sealplate restraint part while one of a female thread or a male threadprovided in the seal plate restraint part is screwed with the other ofthe female thread or the male thread provided in the seal plate toswitch between the seal plate non-restraint state and the seal platerestraint state.

With the method for disassembling/assembling a gas turbine described inthe above (7), since the seal plate non-restraint state and the sealplate restraint state are switched by rotating the seal plate restraintpart while the male thread is screwed with the female thread, even ifforce acts on the seal plate restraint part in the axial direction, theseal plate non-restraint state and the seal plate restraint state arenot easily switched. Thus, it is possible to enhance the effect ofcontrolling switching between the engagement state and thenon-engagement state between the seal plate and the blade at anunintended timing.

Further, since the seal plate non-restraint state and the seal platerestraint state are not switched unless the seal plate restraint part isrotated, it is easy to move the seal plate in the radial direction whilekeeping the seal plate non-restraint state, for instance.

(8) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (7), theseal-plate-restraint-state switching step includes moving the seal platerestraint part along the axial direction against a biasing force of abiasing part biasing the seal plate restraint part to switch from theseal plate restraint state to the seal plate non-restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (8), even if a weaker force than the biasing force of thebiasing part acts on the seal plate restraint part, the seal platerestraint state is not switched to the seal plate non-restraint state.Thus, it is possible to enhance the effect of controlling switchingbetween the engagement state and the non-engagement state between theseal plate and the blade at an unintended timing.

Further, in a case where the method for disassembling/assembling a gasturbine described in the above (8) is the disassembling/assemblingmethod described in the above (7), the biasing force of the biasing partreduces loosening of the thread. Thus, also for this reason, it ispossible to enhance the effect of controlling switching between theengagement state and the non-engagement state between the seal plate andthe blade at an unintended timing.

(9) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (4), theseal-plate-restraint-state switching step includes switching between astate where the seal plate restraint part does not engage with the sealplate and a state where the seal plate restraint part engages with theseal plate to switch between the seal plate non-restraint state and theseal plate restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (9), since the seal plate non-restraint state and the sealplate restraint state are switched by switching between the engagementstate and the non-engagement state between the seal plate restraint partand the seal plate, it is possible to enhance the effect of controllingswitching between the engagement state and the non-engagement statebetween the seal plate and the blade at an unintended timing.

(10) In some embodiments, in the method for disassembling/assembling agas turbine described in the above (9), the seal plate restraint part isa seal plate fall prevention pin extending along the axial direction,and the seal-plate-restraint-state switching step includes switchingbetween a state where a leading end of the seal plate fall preventionpin does not engage with a recess formed in the seal plate and a statewhere the leading end of the seal plate fall prevention pin engages withthe recess formed in the seal plate to switch between the seal platenon-restraint state and the seal plate restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (10), since the seal plate non-restraint state and the sealplate restraint state are switched by moving the seal plate fallprevention pin linearly relative to the recess along the axis of therecess, it is possible to easily switch between the seal platenon-restraint state and the seal plate restraint state.

(11) In some embodiments, in the method for disassembling/assembling agas turbine described in the above (9), the seal plate restraint part isa seal plate fall prevention piece, and the seal-plate-restraint-stateswitching step includes removing the seal plate fall prevention piecemounted in a recess formed in the seal plate from the recess, ormounting the seal plate fall prevention piece in the recess, to switchbetween the seal plate non-restraint state and the seal plate restraintstate.

With the method for disassembling/assembling a gas turbine described inthe above (11), since the seal plate non-restraint state and the sealplate restraint state are switched by removing or mounting the sealplate fall prevention piece from or to the recess of the seal plate, itis possible to easily switch between the seal plate non-restraint stateand the seal plate restraint state.

(12) In some embodiments, in the method for disassembling/assembling agas turbine described in the above (9), the seal-plate-restraint-stateswitching step includes rotating the seal plate restraint part while afemale thread provided in the rotor disc is screwed with a male threadprovided in the seal plate restraint part to switch between the sealplate non-restraint state and the seal plate non-restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (12), since the seal plate non-restraint state and the sealplate restraint state are switched by rotating the seal plate restraintpart while the male thread is screwed with the female thread, even ifforce acts on the seal plate restraint part in the axial direction, theseal plate non-restraint state and the seal plate restraint state arenot easily switched. Thus, it is possible to enhance the effect ofcontrolling switching between the engagement state and thenon-engagement state between the seal plate and the blade at anunintended timing.

Further, since the seal plate non-restraint state and the seal platerestraint state are not switched unless the seal plate restraint part isrotated, it is easy to move the seal plate in the radial direction whilekeeping the seal plate non-restraint state, for instance.

(13) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (6), the seal plateand the seal plate restraint part are formed integrally, and theseal-plate-restraint-state switching step includes plastically deformingthe seal plate restraint part to switch between the seal platenon-restraint state and the seal plate restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (13), since the seal plate non-restraint state and the sealplate restraint state are switched by plastic deformation of the sealplate restraint part, it is possible to easily switch between the sealplate non-restraint state and the seal plate restraint state of the sealplate assembly with a simple configuration.

(14) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (6), theseal-plate-restraint-state switching step includes rotating the sealplate restraint part while a male thread provided in the seal platerestraint part is screwed with a female thread provided in a throughhole penetrating the seal plate to switch between the seal platenon-restraint state and the seal plate restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (14), since the seal plate non-restraint state and the sealplate restraint state are switched by rotating the seal plate restraintpart while the male thread is screwed with the female thread, even ifforce acts on the seal plate restraint part in the axial direction, theseal plate non-restraint state and the seal plate restraint state arenot easily switched. Thus, it is possible to enhance the effect ofcontrolling switching between the engagement state and thenon-engagement state between the seal plate and the blade at anunintended timing.

Further, since the seal plate non-restraint state and the seal platerestraint state are not switched unless the seal plate restraint part isrotated, it is easy to move the seal plate in the radial direction whilekeeping the seal plate non-restraint state, for instance.

(15) In some embodiments, in the method for disassembling/assembling agas turbine described in any one of the above (1) to (14), the methodfurther comprises a blade-restraint-state switching step of moving theseal plate in the radial direction to switch between a bladenon-restraint state where the seal plate does not restrict movement of ablade along the axial direction and a blade restraint state where theseal plate restraint part restricts movement of the blade along theaxial direction.

With the method for disassembling/assembling a gas turbine described inthe above (15), since the seal-plate-restraint-state switching stepdescribed in the above (1) is included, it is easy to appropriatelyswitch between the seal plate restraint state and the seal platenon-restraint state from the opposite side of the rotor disc from theseal plate. Thus, it is easy to appropriately switch between the bladenon-restraint state and the blade restraint state from the opposite sideof the rotor disc from the seal plate, when disassembling or assemblingthe gas turbine.

(16) In some embodiments, in the method for disassembling/assembling agas turbine described in the above (15), a jig engagement recess or ajig engagement protrusion capable of engaging with a jig is formed in asurface of the seal plate which faces toward the second side in theaxial direction, and the blade-restraint-state switching step includesmoving the seal plate in the radial direction while the jig engagementrecess or the jig engagement protrusion engages with the jig to switchbetween the blade non-restraint state and the blade restraint state.

With the method for disassembling/assembling a gas turbine described inthe above (16), in the blade-restraint-state switching step, the sealplate can be easily moved in the radial direction by the jig. Thus, itis easy to appropriately switch between the blade non-restraint stateand the blade restraint state from the opposite side of the rotor discfrom the seal plate, when disassembling or assembling the gas turbine.

(17) In some embodiments, in the method for disassembling/assembling agas turbine described in the above (15) or (16), the method furthercomprises a blade-fitting-state switching step of switching a bladenon-fitting state where the blade is not fitted in the rotor disc and ablade fitting state where the blade is fitted in the rotor disc.

With the method for disassembling/assembling a gas turbine described inthe above (17), it is possible to easily and appropriately switchbetween the blade restraint state where the seal plate restrictsmovement of the blade along the axial direction and the bladenon-fitting state where the blade is not fitted in the rotor disc, onlyby operation on the opposite side of the rotor disc from the seal plate.

(18) According to at least one embodiment of the present invention, aseal plate assembly for a blade of a gas turbine comprises a seal platehaving a first surface and a second surface which face in oppositedirections; and a movable part capable of protruding from the firstsurface at a variable protrusion amount.

With the seal plate assembly described in the above (18), by changingthe protrusion amount of the movable part from the first surface, it ispossible to switch between the seal plate non-restraint state where themovable part does not restrict movement of the seal plate in thedirection along the first surface and the seal plate restraint statewhere the movable part restricts movement of the seal plate in thedirection along the first surface.

Thus, for instance, even if force acts on the movable part in adirection intersecting with the protruding direction of the movable partby friction caused between the outer peripheral surface of the rotordisc and the movable part due to vibration during operation of the gasturbine, or due to acceleration or deceleration of rotation of the rotordisc during operation of the gas turbine, the seal plate non-restraintstate and the seal plate restraint state are not easily switched.

Thus, it is possible to control switching between the engagement stateand the non-engagement state between the seal plate and the blade at anunintended timing.

(19) In some embodiments, in the seal plate assembly described in theabove (18), the seal plate has one of a female thread or a male threadextending along a direction perpendicular to the first surface, and themovable part has the other of the female thread or the male thread whichis screwed with the one of the female thread or the male thread.

With the seal plate assembly described in the above (19), since the sealplate non-restraint state and the seal plate restraint state areswitched by rotating the movable part while the male thread is screwedwith the female thread, even if force acts on the movable part in theaxial direction of the thread, the seal plate non-restraint state andthe seal plate restraint state are not easily switched. Thus, it ispossible to enhance the effect of controlling switching between theengagement state and the non-engagement state between the seal plate andthe blade at an unintended timing.

Further, since the seal plate non-restraint state and the seal platerestraint state are not switched unless the movable part is rotated, itis easy to move the seal plate in the direction along the first surfacewhile keeping the seal plate non-restraint state, for instance.

(20) In some embodiments, in the seal plate assembly described in theabove (19), a surface of the movable part which faces in the samedirection as the first surface is provided with a recess having anon-circular cross-sectional shape.

With the seal plate assembly described in the above (20), by engaging ajig with the recess and thereby rotating the movable part, it ispossible to switch between the seal plate non-restraint state and theseal plate restraint state.

(21) In some embodiments, the seal plate assembly described in the above(19) or (20) further comprises a washer clamped between the movable partand the seal plate.

With the seal plate assembly described in the above (21), loosening ofthe thread is reduced by the washer. Thus, it is possible to enhance theeffect of controlling switching between the engagement state and thenon-engagement state between the seal plate and the blade at anunintended timing.

(22) In some embodiments, the seal plate assembly described in any oneof the above (18) to (21) further comprises a biasing part biasing themovable part in a direction in which the movable part protrudes from thefirst surface.

With the seal plate assembly described in the above (22), even if aweaker force than the biasing force of the biasing part acts on themovable part, the seal plate restraint state is not switched to the sealplate non-restraint state. Thus, it is possible to enhance the effect ofcontrolling switching between the engagement state and thenon-engagement state between the seal plate and the blade at anunintended timing.

Further, in a case where the seal plate assembly described in the above(22) is the seal plate assembly described in the above (19), the biasingforce of the biasing part reduces loosening of the thread. Thus, alsofor this reason, it is possible to enhance the effect of controllingswitching between the engagement state and the non-engagement statebetween the seal plate and the blade at an unintended timing.

(23) In some embodiments, the seal plate assembly described in the above(18) further comprises a biasing part biasing the movable part in adirection in which the movable part protrudes from the first surface,and the seal plate has one of a female thread or a male thread extendingalong a direction perpendicular to the first surface, and the movablepart has the other of the female thread or the male thread which isscrewed with the one of the female thread or the male thread.

With the seal plate assembly described in the above (23), since the sealplate non-restraint state and the seal plate restraint state areswitched by rotating the movable part while the male thread is screwedwith the female thread, even if force acts on the movable part in theaxial direction of the thread, the seal plate non-restraint state andthe seal plate restraint state are not easily switched. Thus, it ispossible to enhance the effect of controlling switching between theengagement state and the non-engagement state between the seal plate andthe blade at an unintended timing.

Further, the biasing force of the biasing part reduces loosening of thethread. Thus, also for this reason, it is possible to enhance the effectof controlling switching between the engagement state and thenon-engagement state between the seal plate and the blade at anunintended timing.

(24) In some embodiments, in the seal plate assembly described in theabove (22) or (23), the biasing part includes a disc spring, a coilspring, or a leaf spring.

With the seal plate assembly described in the above (24), in case ofusing the disc spring as the biasing part, even if cracks occur in thebiasing part, the size of the biasing part in the axial direction of thespring is not likely to become small. Thus, it is possible to bias themovable part relatively stably.

(25) In some embodiments, in the seal plate assembly described in anyone of the above (18) to (24), the seal plate includes a plate part andan accommodation chamber forming part forming an accommodation chamberfor accommodating the movable part, and the movable part is configuredso that at least a part of the movable part is capable of protrudingfrom an opening formed in the first surface of the accommodation chamberforming part.

With the seal plate assembly described in the above (25), since theaccommodation chamber forming part for at least partially accommodatingthe movable part is provided, it is possible to achieve the effects ofthe seal plate assembly described in any one of the above (18) to (24)while suppressing the reduction in seal performance of the seal plate.

(26) In some embodiments, in the seal plate assembly described in theabove (25), the accommodation chamber forming part protrudes from theplate part in a direction in which the second surface faces.

With the seal plate assembly described in the above (26), it is possibleto achieve the effects of the seal plate assembly described in the above(25) while ensuring a space allowing the movable part to move.

(27) In some embodiments, in the seal plate assembly described in theabove (26), the accommodation chamber forming part protrudes from theplate part in the direction in which the second surface faces in both arange where the movable part exists in a width direction of the sealplate and a range where the movable part does not exist in the widthdirection.

If the accommodation chamber forming part protrudes in the direction inwhich the second surface faces only in a range where the movable partexists in the width direction, windage loss occurs due to the protrudingportion of the accommodation chamber forming part when the gas turbinerotor rotates in response to operation of the gas turbine, which causesthe reduction in gas turbine efficiency.

In view of this, as described in the above (27), with the configurationin which the accommodation chamber forming part protrudes in both arange where the movable part exists in the circumferential direction anda range where the movable part does not exist in the circumferentialdirection, it is possible to reduce the windage loss.

Herein, “width direction” corresponds to a direction (circumferentialdirection) perpendicular to each of the protruding direction (radialdirection) of the projection of the seal plate and the thicknessdirection (axial direction) of the seal plate and corresponds to adirection perpendicular to each of the extension direction (radialdirection) of stepped portions disposed on both sides of the seal platewhere adjacent seal plates overlap and the protruding direction (axialdirection) of the movable part in the following detailed description.

(28) In some embodiments, in the seal plate assembly described in theabove (26) or (27), the accommodation chamber forming part protrudesfrom the plate part in the direction in which the second surface facesover a range of 80% or more of a length of the seal plate in a widthdirection of the seal plate.

With the seal plate assembly described in the above (28), since theaccommodation chamber forming part protrudes from the plate part in adirection in which the second surface faces over most of the range inthe width direction, it is possible to suppress the increase in windageloss, compared with the case where the accommodation chamber formingpart protrudes locally in the range in the width direction.

(29) In some embodiments, in the seal plate assembly described in anyone of the above (25) to (28), the accommodation chamber forming parthas a thinned portion at a different position from the accommodationchamber.

With the seal plate assembly described in the above (29), it is possibleto adjust the stiffness of the seal plate by provision of the thinnedportion. By adjusting the stiffness of the seal plate, it is possible toadjust the natural frequency of the blade. By adjusting the naturalfrequency of the blade, it is possible to suppress the occurrence ofresonance of the blade.

(30) In some embodiments, in the seal plate assembly described in anyone of the above (18) to (29), the movable part is disposed away from acenter of the seal plate in a width direction of the seal plate.

During operation of the gas turbine, since centrifugal force acts oncomponents of the gas turbine rotor, the seal plate is pressed radiallyoutward toward the blade. Accordingly, if the boundary position betweenadjacent seal plates is positioned between the blade roots of blades sothat one seal plate is pressed to one blade during operation, structuralstability can be obtained.

In this regard, in the seal plate assembly described in the above (30),in the case where the boundary position between adjacent seal plates ispositioned between blade roots of two adjacent blades to obtain theabove advantage, since the movable part is disposed away from the centerof the seal plate in the width direction of the seal plate, it ispossible to make use of the space between the adjacent blades as apassage for a jig to operate the movable part.

(31) In some embodiments, in the seal plate assembly described in theabove (30), the seal plate has a projection protruding from an edge ofthe seal plate extending in the width direction, and the projection islocated across the center of the seal plate in the width direction fromthe movable part.

With the seal plate assembly described in the above (31), by causing theprojection to abut on a step provided in the blade, it is possible torestrict movement of the seal plate in the width direction relative tothe blade.

(32) According to at least one embodiment of the present invention, aseal plate assembly for a blade of a gas turbine comprises: a seal platehaving a first surface and a second surface which face in oppositedirections and having a recess formed in the first surface; and a recessengagement member engaging with the recess and extending along adirection perpendicular to the first surface.

With the seal plate assembly described in the above (32), since the sealplate non-restraint state and the seal plate restraint state areswitched by moving the recess engagement member linearly relative to therecess along the perpendicular direction, it is possible to easilyswitch between the seal plate non-restraint state and the seal platerestraint state.

(33) According to at least one embodiment of the present invention, agas turbine rotor comprises: a rotor disc; a plurality of blades mountedon the rotor disc; and at least one seal plate assembly for the blades.The at least one seal plate assembly includes the seal plate assemblydescribed in any one of the above (18) to (32).

With the gas turbine rotor described in the above (33), since the sealplate assembly described in any one of the above (18) to (32) isincluded, it is possible to control switching between the engagementstate and the non-engagement state between the seal plate and the bladeat an unintended timing.

(34) In some embodiments, the gas turbine rotor described in the above(33) further comprises: a locking plate for holding the seal platebetween the locking plate and an end surface of the rotor disc; and alocking piece configured to press the locking plate toward the endsurface of the rotor disc.

With the gas turbine rotor described in the above (34), when theengagement state and the non-engagement state between the seal plate andthe blade are switched on the second surface side of the seal plateassembly, the switching can be easily performed by mounting or removingthe locking piece and the locking plate.

(35) According to at least one embodiment of the present invention, agas turbine rotor comprises: a rotor disc; a plurality of blades mountedon the rotor disc; and at least one seal plate assembly for the blades.The at least one seal plate assembly includes a pair of seal plateassemblies which are adjacent to each other in a circumferentialdirection of the rotor disc, and each of the pair of seal plateassemblies is the seal plate assembly described in any one of the above(18) to (32).

With the gas turbine rotor described in the above (35), since theadjacent seal plate assemblies of the pair are the seal plate assembliesdescribed in any one of the above (18) to (32), it is possible tocontrol switching between the engagement state and the non-engagementstate between the seal plate and the blade at an unintended timing.

Further, through a space caused by removing a pair of bladescorresponding to the pair of seal plate assemblies from the rotor disc,other seal plates at different positions from the pair of seal plateassemblies can be moved in the circumferential direction and thereby canbe easily removed from respective blades. Thus, it is possible toefficiently disassemble the gas turbine.

(36) According to at least one embodiment of the present invention, agas turbine rotor comprises: a rotor disc; a plurality of blades mountedon the rotor disc; and at least one seal plate assembly for the blades.The at least one seal plate assembly includes a plurality of seal plateassemblies arranged symmetrically around a rotation center of the rotordisc, and each of the plurality of seal plate assemblies arrangedsymmetrically is the seal plate assembly described in any one of theabove (18) to (32).

With the gas turbine rotor described in the above (36), since the sealplate assemblies arranged symmetrically around the rotation center ofthe rotor disc are the seal plate assemblies described in any one of theabove (18) to (32), it is possible to control switching between theengagement state and the non-engagement state between the seal plate andthe blade at an unintended timing in the seal plate assembly.

Further, through spaces caused by removing a plurality of bladescorresponding to the plurality of seal plate assemblies from the rotordisc, other seal plates at different positions from the plurality ofseal plate assemblies can be moved in the circumferential direction andthereby can be easily removed from respective blades.

Further, since the spaces caused by removing the plurality of bladescorresponding to the plurality of seal plate assemblies from the rotordisc are positioned symmetrically with respect to the rotation center ofthe rotor disc, it is possible to remove the blades by moving the otherseal plates in the circumferential direction a short distance. Thus, itis possible to efficiently disassemble the gas turbine.

(37) According to at least one embodiment of the present invention, agas turbine rotor comprises: a rotor disc; a plurality of blades mountedon the rotor disc; and the seal plate assembly described in any one ofthe above (18) to (32), in which the seal plate includes a plate partand an accommodation chamber forming part forming an accommodationchamber for accommodating the movable part, the accommodation chamberforming part protrudes from the plate part in a direction in which thesecond surface faces, the gas turbine rotor further comprises a sealplate not provided with the movable part, and the seal plate notprovided with the movable part includes a plate part and a projectingpart protruding from the plate part in a direction in which the secondsurface faces.

In the gas turbine rotor described in the above (37), the direction inwhich the accommodation chamber forming part protrudes from the platepart of the seal plate assembly (direction in which second surfacefaces) coincides with the direction in which the projecting part of theseal plate not provided with the movable part protrudes from the sealplate. Thus, by making the difference in protrusion amount between theaccommodating chamber forming part and the projecting part close tozero, it is possible to suppress the increase in windage loss due toprotrusion of the accommodating chamber forming part during rotation ofthe gas turbine rotor.

(38) According to at least one embodiment of the present invention, agas turbine rotor comprises: a rotor disc; a plurality of blades mountedon the rotor disc; and the seal plate assembly described in any one ofthe above (18) to (32), in which the seal plate includes a plate partand an accommodation chamber forming part forming an accommodationchamber for accommodating the movable part, the accommodation chamberforming part protrudes from the plate part in a direction in which thesecond surface faces, the accommodation chamber forming part has a firstthinned portion at a position different from the accommodation chamber,the gas turbine rotor further comprises another seal plate not providedwith the movable part, the another seal plate includes a plate part anda projecting part protruding from the plate part in a direction in whichthe second surface faces, and the projecting part has a second thinnedportion having a different dimension from the first thinned portion.

With the gas turbine rotor described in the above (38), by makingdifference between the dimension of the first thinned portion formed inthe accommodation chamber forming part of the seal plate with themovable part and the dimension of the second thinned portion formed inthe projecting part of the other seal plate with no movable part, it ispossible to adjust the stiffness of each seal plate. By adjusting thestiffness of the seal plate, it is possible to adjust the naturalfrequency of the blade. By adjusting the natural frequency of the blade,it is possible to suppress the occurrence of resonance of the blade.

(39) According to at least one embodiment of the present invention, agas turbine comprises: the gas turbine rotor described in any one of theabove (33) to (38) and a casing covering the gas turbine rotor.

With the gas turbine rotor described in the above (39), since the gasturbine rotor described in any one of the above (33) to (38) isincluded, it is possible to control switching between the engagementstate and the non-engagement state between the seal plate and the bladeat an unintended timing.

(40) According to at least one embodiment of the present invention, amethod for producing a gas turbine including a seal plate disposed on afirst side of a rotor disc in an axial direction of the rotor disc and aseal plate restraint part for restricting movement of the seal platerelative to the rotor disc in a radial direction of the rotor disccomprises a seal-plate-restraint-state switching step of moving the sealplate restraint part along the axial direction to switch from a sealplate non-restraint state where the seal plate restraint part does notrestrict movement of the seal plate in the radial direction to a sealplate restraint state where at least a part of the seal plate restraintpart protrudes in the axial direction from the seal plate and therebyrestricts movement of the seal plate in the radial direction.

With the method for producing a gas turbine described in the above (40),in the seal-plate-restraint-state switching step, the seal platenon-restraint state and the seal plate restraint state are switched bymoving the seal plate restraint part along the axial direction.

Thus, for instance, even if force acts on the seal plate restraint partin a direction different from the axial direction of the seal platerestraint part by friction caused between the outer peripheral surfaceof the rotor disc and the seal plate restraint part due to vibrationduring operation of the gas turbine, or due to acceleration ordeceleration of rotation of the rotor disc during operation of the gasturbine, the seal plate non-restraint state and the seal plate restraintstate are not easily switched.

Thus, it is possible to control switching between the engagement stateand the non-engagement state between the seal plate and the blade at anunintended timing.

Advantageous Effects

According to at least one embodiment of the present invention, there isprovided a method for disassembling/assembling a gas turbine, a sealplate assembly, and a gas turbine rotor including the same whereby it ispossible to control switching between the engagement state and thenon-engagement between the seal plate and the blade at an unintendedtiming.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of a gas turbine 2 accordingto an embodiment of the present invention, taken along the rotationalaxis of the gas turbine 2.

FIG. 2 is a schematic configuration diagram of a blade 22.

FIG. 3 is a schematic configuration diagram of a blade groove 26 formedin an outer peripheral surface 24 of a gas turbine rotor 16.

FIG. 4 is a diagram for describing the configuration of a seal plateassembly 42(42A) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 5 is a diagram for describing the configuration of a seal plateassembly 42(42A) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 6 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 of a seal plate assembly 42(42A), taken alongthe axial direction.

FIG. 7 is a schematic diagram showing the arrangement of a plurality ofseal plate assemblies 42(42A), viewed from downstream in the axialdirection.

FIG. 8 is a schematic diagram showing a seal plate assembly 42(42A),viewed from upstream in the axial direction.

FIG. 9 is a schematic diagram showing a seal plate assembly, viewed fromdownstream in the axial direction.

FIG. 10 is a schematic cross-sectional view taken along line A-A in FIG.8.

FIG. 11 is a schematic diagram of a seal plate 110 according to anembodiment, viewed from upstream in the axial direction.

FIG. 12 is a schematic diagram of the seal plate 110 according to anembodiment, viewed from downstream in the axial direction.

FIG. 13 is a schematic cross-sectional view taken along line B-B in FIG.11.

FIG. 14 is a diagram showing the circumferential arrangement of sealplate assemblies 42 and seal plates 110 in a gas turbine rotor 16according to an embodiment.

FIG. 15 is a diagram for describing a method for disassembling a gasturbine 2 according to an embodiment.

FIG. 16 is a diagram for describing a method for disassembling a gasturbine 2 according to an embodiment.

FIG. 17 is a diagram for describing a method for disassembling a gasturbine 2 according to an embodiment.

FIG. 18 is a diagram for describing a method for disassembling a gasturbine 2 according to an embodiment.

FIG. 19 is a diagram for describing a method for disassembling a gasturbine 2 according to an embodiment.

FIG. 20 is a diagram for describing a method for assembling a gasturbine 2 according to an embodiment.

FIG. 21 is a diagram for describing a method for assembling a gasturbine 2 according to an embodiment.

FIG. 22 is a diagram for describing a method for assembling a gasturbine 2 according to an embodiment.

FIG. 23 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42B)according to an embodiment, taken along the axial direction.

FIG. 24 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42C)according to an embodiment, taken along the axial direction.

FIG. 25 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42D)according to an embodiment, taken along the axial direction.

FIG. 26 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42D)according to an embodiment, taken along the axial direction.

FIG. 27 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42E)according to an embodiment, taken along the axial direction.

FIG. 28 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42E)according to an embodiment, taken along the axial direction.

FIG. 29 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42F)according to an embodiment, taken along the axial direction.

FIG. 30 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42F)according to an embodiment, taken along the axial direction.

FIG. 31 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42G)according to an embodiment, taken along the axial direction.

FIG. 32 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42G)according to an embodiment, taken along the axial direction.

FIG. 33 is a diagram for describing the configuration of a seal plateassembly 42(42H) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 34 is a diagram for describing the configuration of a seal plateassembly 42(42H) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 35 is a diagram for describing the configuration of a seal plateassembly 42(42H) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 36 is a diagram for describing the configuration of a seal plateassembly 42(42I) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 37 is a diagram for describing the configuration of a seal plateassembly 42(42I) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 38 is a diagram for describing the configuration of a seal plateassembly 42(42J) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 39 is a schematic diagram showing the arrangement of seal platerestraint parts 46 of seal plate assemblies 42(42J), viewed fromdownstream in the axial direction.

FIG. 40 is a diagram showing a state where a seal plate restraint part46 is removed in a seal plate assembly 42(42J) according to anembodiment.

FIG. 41 is a diagram for describing the configuration of a seal plateassembly 42(42K) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 42 is a schematic diagram showing the arrangement of seal platerestraint parts 46 of seal plate assemblies 42(42K), viewed fromdownstream in the axial direction.

FIG. 43 is a diagram for describing the configuration of a seal plateassembly 42(42M) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 44 is a diagram for describing the configuration of a seal plateassembly 42(42M) according to an embodiment, which shows a partialcross-section of a gas turbine rotor 16 taken along the axial direction.

FIG. 45 is a plan view showing a configuration example of an inspectiondevice for identifying the assembly state of a seal plate assembly 42.

FIG. 46 is a diagram of an inspection device viewed from upstream in theinsertion direction of an inspection rod.

FIG. 47 is a diagram showing a usage state of the inspection deviceshown in FIGS. 45 and 46.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described in detailwith reference to the accompanying drawings. It is intended, however,that unless particularly identified, dimensions, materials, shapes,relative positions and the like of components described in theembodiments shall be interpreted as illustrative only and not intendedto limit the scope of the present invention.

For instance, an expression of relative or absolute arrangement such as“in a direction”, “along a direction”, “parallel”, “orthogonal”,“centered”, “concentric” and “coaxial” shall not be construed asindicating only the arrangement in a strict literal sense, but alsoincludes a state where the arrangement is relatively displaced by atolerance, or by an angle or a distance whereby it is possible toachieve the same function.

For instance, an expression of an equal state such as “same” “equal” and“uniform” shall not be construed as indicating only the state in whichthe feature is strictly equal, but also includes a state in which thereis a tolerance or a difference that can still achieve the same function.

Further, for instance, an expression of a shape such as a rectangularshape or a cylindrical shape shall not be construed as only thegeometrically strict shape, but also includes a shape with unevenness orchamfered corners within the range in which the same effect can beachieved.

On the other hand, an expression such as “comprise”, “include”, “have”,“contain” and “constitute” are not intended to be exclusive of othercomponents.

(Schematic Configuration of Gas Turbine)

FIG. 1 is a schematic cross-sectional view of a gas turbine 2 accordingto an embodiment of the present invention, taken along the rotationalaxis of the gas turbine 2.

As shown in FIG. 1, the gas turbine 2 includes a compressor 4 forcompressing air to produce compressed air, a combustor 6 for mixing thecompressed air with fuel supplied from a fuel supply source (not shown)and combusting the mixture to produce combustion gas, and a turbine 8rotationally driven by the combustion gas.

The turbine 8 includes a turbine casing 10, a plurality of vane rows 12fixed to an inner side of the turbine casing 10, and a gas turbine rotor16 including a plurality of blade rows 14 and configured to rotatewithin the turbine casing 10. The gas turbine rotor 16 includes aplurality of rotor discs 18 arranged in the axial direction of the rotorand mutually connected. Each of the rotor discs 18 is mounted with acorresponding one of the blade rows 14. The vane rows 12 and the bladerows 14 are arranged alternately along the axial direction of the gasturbine rotor 16.

Each of the vane rows 12 includes a plurality of vanes 20 arranged inthe circumferential direction of the gas turbine rotor 16, and each ofthe vanes 20 is fixed to the inner side of the turbine casing 10. Eachof the blade rows 14 includes a plurality of blades 22 arranged in thecircumferential direction of the gas turbine rotor 16, and each of theblades 22 is mounted to an outer peripheral surface of the rotor disc18.

Hereinafter, unless otherwise stated, the axial direction of the gasturbine rotor 16 (axial direction of the rotor disc 18) is referred toas merely “axial direction” or “axially”, and the circumferentialdirection of the gas turbine rotor 16 (circumferential direction of therotor disc 18) is referred to as merely “circumferential direction” or“circumferentially”, and the radial direction of the gas turbine rotor16 (radial direction of the rotor disc 18) is referred to as merely“radial direction” or “radially”. Further, the upstream side and thedownstream side of a combustion gas flow in the axial direction arereferred to as merely “upstream side in axial direction” or “axiallyupstream side” and “downstream side in axial direction” or “axiallydownstream side”, respectively.

FIG. 2 is a schematic configuration diagram of the blade 22. FIG. 3 is aschematic configuration diagram of a blade groove 26 formed in the outerperipheral surface 24 of the gas turbine rotor 16.

As shown in FIG. 2, the blade 22 includes a blade body 28, a platform 30disposed on an inner side of the blade body 28 in the radial direction,a shank 32 disposed on an inner side of the platform 30 in the radialdirection, and a blade root 34 disposed on an inner side of the shank 32in the radial direction. An inner peripheral surface of an axiallydownstream end portion of the platform 30 has an outer groove 36recessed outward in the radial direction and extending in thecircumferential direction. The cross-section of the blade root 34(cross-section perpendicular to the chordwise direction of the bladebody 28) has a Christmas-tree-like shape having alternate enlarged andreduced width portions in which the width in the circumferentialdirection increases and decreases alternately toward the inner side inthe radial direction. Further, a clearance 38 is provided between theshanks 32 of two adjacent blades 22 so that cooling air flows into theclearance 38 to cool the blades 22.

As shown in FIG. 3, the outer peripheral surface 24 of the rotor disc 18has a blade groove 26 into which the blade root 34 of the blade 22 isfitted. The blade groove 26 extends through the rotor disc 18 from theupstream end to the downstream end of the rotor disc 18 in the axialdirection and has a cross-sectional shape corresponding to theChristmas-tree-like shape of the blade root 34. With the aboveconfiguration, by inserting the blade root 34 of the blade 22 into theblade groove 26 along the axial direction and fitting the blade root 34into the blade groove 26, the blade 22 is restrained in thecircumferential direction and in the radial direction. Further, therotor disc 18 has an inner groove 40 formed downstream of the bladegroove 26, recessed inward in the radial direction, and extending in thecircumferential direction. Herein, “outer peripheral surface 24 of rotordisc 18” means a surface of the rotor disc 18 in which the blade groove26 is formed, and does not include a surface in which the inner groove40 is formed.

(Configuration of Seal Plate Assembly)

FIG. 4 is a diagram for describing the configuration of a seal plateassembly 42(42A) according to an embodiment, which shows a partialcross-section of the gas turbine rotor 16 taken along the axialdirection.

The gas turbine rotor 16 includes a plurality of seal plate assemblies42(42A) for a plurality of blades 22.

In some embodiments, as shown in FIG. 4, the seal plate assembly 42(42A)includes a seal plate 44 disposed downstream of the rotor disc 18 in theaxial direction, and a seal plate restraint part 46 for restrictingmovement of the seal plate 44 relative to the rotor disc 18 in theradial direction. In the illustrated embodiment, the seal platerestraint part 46 is configured as a plug 45.

The seal plate 44 has a radially outer end portion 48 configured to befitted into the outer groove 36 of the blade 22 and thereby engages withthe blade 22 to restrict movement of the blade 22 along the axialdirection. Further, the outer groove 36 restricts movement of the sealplate 44 in the radial direction to prevent radially outward movement ofthe seal plate 44. The seal plate 44 has a first surface 50 and a secondsurface 52 which face in opposite directions. The first surface 50 facesupstream in the axial direction, while the second surface 52 facesdownstream in the axial direction.

The seal plate restraint part 46 is configured to be switchable betweena seal plate restraint state (see FIG. 4) where at least a part of theseal plate restraint part 46 protrudes upstream in the axial directionfrom the seal plate 44 and thereby restricts movement of the seal plate44 in the radial direction and a seal plate non-restraint state (seeFIG. 5) where movement of the seal plate 44 is not restricted in theradial direction. In the illustrated embodiment, the seal platerestraint part 46 is configured as a movable part capable of protrudingfrom the first surface 50 at a variable protrusion amount. The sealplate restraint part 46 engages with the rotor disc 18 in such a mannerthat the peripheral surface of the seal plate restraint part 46 iscaught on the outer peripheral surface 24 of the rotor disc 18, therebyrestricting radially inward movement of the seal plate 44. Theprotruding direction (moving direction) of the seal plate restraint part46 may not be parallel to the axial direction but includes an axialcomponent. For instance, the seal plate restraint part 46 may protrude(move) along the extension direction of the blade groove 26.

Further, in the illustrated embodiment, the gas turbine rotor 16includes a locking plate 56 for holding the seal plate 44 between thelocking plate 56 and a downstream end surface 54 of the rotor disc 18,and a locking piece 58 configured to press the locking plate 56 to theend surface 54 of the rotor disc 18. The locking plate 56 and thelocking piece 58 are held in the inner groove 40 of the rotor disc 18.

The locking plate 56 includes a plate body part 60 extending in theradial direction along the end surface 54 on the downstream side of thegas turbine rotor 16, a rising part 62 extending downward from aradially outer end portion of the plate body part 60, and a lap part 66extending radially outward from a downstream end portion of the risingpart 62 and overlapping a radially inner end portion 64 of the sealplate 44 in the radial direction. Thus, the locking plate 56 has acrank-shaped cross-section. The lap part 66 is disposed with a gap fromthe end surface 54 on the downstream side of the gas turbine rotor 16,and the radially inner end portion 64 of the seal plate 44 is heldwithin the gap. As shown in FIG. 4, in a state where the seal platerestraint part 46 engages with the outer peripheral surface 24 of therotor disc 18, a distance A between the radially inner end portion 64 ofthe seal plate 44 and the rising part 62 in the radial direction islarger than a depth B of the outer groove 36 (depth based on adownstream edge 63 of the outer groove 36). Thus, by moving the sealplate 44 radially inward by a distance equal to or more than thedimension B, it is possible to release the restriction of axiallyupstream movement of the blade 22 by the seal plate 44.

The locking piece 58 includes a support plate 68 and a pressing screw70. The support plate 68 is disposed downstream of the plate body part60 in the axial direction so as to adjoin the plate body part 60 andextends along the plate body part 60 in the radial direction. Thepressing screw 70 is screwed into the support plate 68. In response torotation of the pressing screw 70, the support plate 68 is separatedfrom the locking plate 56 in the axial direction, and the support plate68 and the locking plate 56 are fixed to the inner groove 40 by tension.

FIG. 6 is an enlarged cross-sectional view of the vicinity of the sealplate restraint part 46 of the seal plate assembly 42(42A), taken alongthe axial direction.

As shown in FIG. 6, the seal plate 44 includes a plate part 72 extendingin the radial direction and an accommodation chamber forming part 76forming an accommodation chamber 74 for at least partially accommodatingthe seal plate restraint part 46. The seal plate restraint part 46 isconfigured so that a part of the seal plate restraint part 46 is capableof protruding from an opening 78 formed in an axially upstream portion(first surface 50 of seal plate 44) of the accommodation chamber formingpart 76. The accommodation chamber forming part 76 is provided in aradially outer portion of the seal plate 44 and protrudes downstream inthe axial direction (direction to which second surface 52 faces) fromthe plate part 72.

The accommodation chamber forming part 76 of the seal plate 44 includesa cylindrical part 82 extending upstream in the axial direction from awall part 80 disposed downstream in the axial direction, and a femalethread 84 extending along the axial direction (direction perpendicularto first surface 50) is formed in an inner peripheral surface of thecylindrical part 82.

An axially downstream end portion of the seal plate restraint part 46has a male thread 86 configured to be screwed with the female thread 84.The seal plate restraint part 46 includes a brim part 88 adjoining theaxially upstream side of the male thread 86 and protruding in the radialdirection of the male thread 86, and a protruding part 90 protrudingupstream in the axial direction from the brim part 88.

The protruding part 90 of the seal plate restraint part 46, i.e., theaxially upstream end portion of the seal plate restraint part 46 has ajig engagement portion 92 capable of engaging with a jig for rotatingthe seal plate restraint part 46. The jig engagement portion 92 isformed as a recess having a non-circular (e.g., hexagonal)cross-sectional shape in a surface of the protruding part 90 of the sealplate restraint part 46 which faces in the same direction as the firstsurface 50.

The seal plate assembly 42(42A) includes a biasing part 94 disposed onthe outer peripheral side of the cylindrical part 82 and configured tobias the brim part 88 upstream in the axial direction. The biasing part94 biases the seal plate restraint part 46 in a direction in which theseal plate restraint part 46 protrudes from the first surface 50. Thebiasing part 94 includes, for instance, a disc spring, a coil spring, ora leaf spring. In case of using the disc spring as the biasing part 94,even if cracks occur in the biasing part 94, the axial size of thebiasing part 94 is not likely to become small. Thus, it is possible tobias the seal plate restraint part 46 relatively stably. In theillustrated embodiment, an annular spacer 193 is provided on the outerperipheral side of the cylindrical part 82. The annular spacer 193 issandwiched between the wall part 80 and the disc spring serving as thebiasing part 94.

The accommodation chamber forming part 76 includes a brim restraint part96 disposed upstream of the brim part 88 in the axial direction torestrict axially upstream movement of the brim part 88. The opening 78is provided in the brim restraint part 96, and a part of the protrudingpart 90 is configured to protrude upstream in the axial direction fromthe opening 78 in a state where the brim part 88 abuts on the brimrestraint part 96.

FIG. 7 is a schematic diagram showing the arrangement of a plurality ofseal plate assemblies 42(42A), viewed from downstream in the axialdirection.

As shown in FIG. 7, the seal plate assemblies 42(42A) are arranged inthe circumferential direction, and a circumferential end portion of theseal plate 44 of each seal plate assembly 42(42A) is superimposed on acircumferential end portion of another circumferentially adjacent sealplate 44 (or seal plate 110 described later) to form a stepped portion98 where the circumferential end portions of the two adjacent sealplates 44 overlap each other. This structure prevents leakage of coolingair in the clearance 38 through a gap between the circumferential endportions of the circumferentially adjacent seal plates 44 to a spacedownstream of the rotor disc 18 in the axial direction.

The clearance 38 is formed between a region 128 on the outer peripheralsurface 24 of the rotor disc 18 except the blade groove 26 and theplatform 30 of the blade 22, as shown in FIG. 7. Further, the jigengagement portion 92 of the seal plate restraint part 46 is disposed tooverlap the clearance 38 when viewed in the axial direction. Here, whenthe radially outermost position of a portion fitted with the blade 22 onthe outer peripheral surface 24 of the rotor disc 18 is defined asposition P, the blade groove 26 means a portion of the outer peripheralsurface 24 positioned radially inside the position P. Further, theregion 128 means a portion of the outer peripheral surface 24 positionedradially outside the position P.

Further, the radially outer end portion 48 (upper edge) of the sealplate 44 is provided with a projection 100 protruding radially outward.The projection 100 is disposed across the center of the seal plate 44 inthe circumferential direction from the seal plate restraint part 46. Theradially outer end portion 48 of the seal plate 44 and the projection100 are together fitted into the outer groove 36 (see FIG. 6). At thistime, the projection 100 of the seal plate 44 abuts on a step (notshown) provided in the outer groove 36 and thereby restricts movement ofthe seal plate 44 in the circumferential direction. In otherembodiments, the projection 100 and the seal plate restraint part 46 maybe positioned on the same side of the center of the seal plate 44 in thecircumferential direction, or the projection 100 may be positioned atthe center of the seal plate 44 in the circumferential direction.Alternatively, the seal plate restraint part 46 may be positioned at thecenter of the seal plate 44 in the circumferential direction.

FIG. 8 is a schematic diagram showing the seal plate assembly 42(42A),viewed from upstream in the axial direction. FIG. 9 is a schematicdiagram showing the seal plate assembly, viewed from downstream in theaxial direction. FIG. 10 is a schematic cross-sectional view taken alongline A-A in FIG. 8. In the illustrated exemplary embodiment, the sealplate 44 is formed in a rectangular shape when viewed in the axialdirection, in which the long-side direction of the seal plate 44coincides with the circumferential direction, the short-side directionof the seal plate 44 coincides with the radial direction, and thethickness direction of the seal plate 44 coincides with the axialdirection. In the illustrated embodiment, the width direction of theseal plate 44 is perpendicular to each of the protruding direction(radial direction) of the projection 100 of the seal plate 44 and thethickness direction (axial direction) of the seal plate 44. Further, thewidth direction of the seal plate 44 is perpendicular to each of theextension direction (radial direction) of the stepped portions 98disposed on both circumferential ends of the seal plate 44 to overlapflanking seal plates 44 and the protruding direction (axial direction)of the seal plate restraint part 46.

As shown in FIGS. 6 and 10, the accommodation chamber forming part 76protrudes downstream in the axial direction (direction to which secondsurface 52 faces) from the plate part 72 in both a range where the sealplate restraint part 46 exists in the circumferential direction (widthdirection of seal plate 44) (see FIG. 6) and a range where the sealplate restraint part 46 does not exist in the circumferential direction(see FIG. 10). As shown in FIGS. 6 and 10, an axially downstream endsurface 102 of the accommodation chamber forming part 76 is formed alonga plane perpendicular to the axial direction. Further, as shown in FIG.9, the accommodation chamber forming part 76 protrudes downstream in theaxial direction from the plate part 72 over a range W1 which is 80% ormore of an existence range W0 where the seal plate 44 exists in thecircumferential direction. In the embodiment shown in FIG. 9, theaccommodation chamber forming part 76 protrudes downstream uniformlyover the entire circumferential range W1 except for a range where thestepped portion 98 is formed on one circumferential side of thedownstream surface of the seal plate 44.

As shown in FIG. 10, the plate part 72 of the seal plate 44 includes twoor more portions having different thicknesses. In the illustratedembodiment, the thickness t1 of the radially inner end portion 64 of theplate part 72 is larger than the thickness t2 of a portion 105 of theplate part 72 between the radially inner end portion 64 and theaccommodation chamber forming part 76.

As shown in FIG. 8, the accommodation chamber forming part 76 has atleast one recessed or thinned portion 104 (first thinned part) at aposition different from the accommodation chamber 74. In the illustratedexemplary embodiment, the at least one thinned portion 104 includes aplurality of thinned portions 104 disposed on different positions fromthe accommodation chamber 74 in the circumferential direction, and eachof the thinned portions 104 is disposed in a range overlapping theaccommodation chamber 74 in the radial direction. Further, thecircumferential size S1 of the thinned portion 104 is larger than thecircumferential size S2 of the protruding part 90 of the seal platerestraint part 46, and the radial size S3 of the thinned portion 104 islarger than the radial size S4 of the protruding part 90 of the sealplate restraint part 46. In other embodiments, the magnituderelationship between the sizes S1, S2, S3, S4 may be different from theabove relationship.

By adjusting the size, shape, number or arrangement of the thinnedportion appropriately, it is possible to adjust the stiffness of theblade 22 and adjust the natural frequency. As shown in FIG. 8, a jigengagement recess 108 capable of engaging with a jig is formed in thefirst surface 50 of the seal plate 44. The jig engagement recess 108 isconfigured as at least one slot having a circumferential length S5longer than a radial length S6. In the illustrated exemplary embodiment,one jig engagement recess 108 is provided on each of the circumferentialends of the seal plate 44. As shown in FIG. 7, each jig engagementrecess 108 is positioned so as to overlap the clearance 38 between aregion of the outer peripheral surface 24 of the rotor disc 18 exceptthe blade groove 26 and the platform of the blade 22 (clearance betweenshanks 32), when viewed in the axial direction. Further, a direction ofa straight line connecting these jig engagement recesses 108 coincideswith the width direction of the seal plate 44. In other embodiments, ajig engagement protrusion capable of engaging with a jig may be formedon the first surface 50 of the seal plate 44.

Generally, a blade is inserted into a blade groove extending obliquelywith respect to the axial direction of a rotor disc. Accordingly, forinstance, in a case where a rod-like jig is inserted into the clearance38 between the blades 22 on the radially inner side of the platforms 30of the blades 22 shown in FIG. 7 to move the seal plate 44 in the radialdirection by the jig, the jig engagement recesses 108 is preferablyconfigured as a slot having a circumferential length S5 longer than aradial length S6, as described above. Thereby, it is possible to easilyinert a rod-like jig into the jig engagement recesses 108 while the jigis inclined with respect to the first surface 50 (axially upstreamfacing surface) of the seal plate 44. Thus, it is easy to move the sealplate 44 in the radial direction.

FIG. 11 is a schematic diagram of a seal plate 110 according to anembodiment, viewed from upstream in the axial direction. FIG. 12 is aschematic diagram of the seal plate 110 according to an embodiment,viewed from downstream in the axial direction. FIG. 13 is a schematiccross-sectional view taken along line B-B in FIG. 11. FIG. 14 is adiagram showing the circumferential arrangement of the seal plateassemblies 42 and the seal plates 110 in the gas turbine rotor 16according to an embodiment.

In an embodiment, as shown in FIGS. 11 to 14, the gas turbine rotor 16includes a seal plate assembly 42 and a plurality of seal plates 44 eachdisposed at a position different from the seal plate assembly 42 and notprovided with the seal plate restraint part 46.

As shown in FIGS. 11 to 13, the seal plate 110 includes a plate part 112and a projecting part 114 protruding downstream in the axial direction(direction to which second surface 52 of seal plate 44 faces) from theplate part 112. The projecting part 114 includes at least one recessedor thinned portion 116 (second thinned portion) having differentdimension from the thinned portion 104. In the illustrated embodiment,the at least one thinned portion 116 includes a plurality of thinnedportions 116 arranged in the circumferential direction. The radial sizeS7 of each thinned portion 116 is larger than the circumferential sizeS8 of each thinned portion 116. Further, the radial dimension h2 of aportion of the seal plate 110 except a projection 122 described later islarger than the radial dimension h1 of a portion of the seal plate 44except the projection 100.

The seal plates 110 are arranged in the circumferential direction, and acircumferential end portion of each seal plate 110 is superimposed on acircumferential end portion of another circumferentially adjacent sealplate 110 to form a stepped portion 118 where the circumferential endportions of the two adjacent seal plates 110 overlap each other. Thisstructure prevents leakage of cooling air in the clearance 38 through agap between the circumferential end portions of the circumferentiallyadjacent seal plates 110 to combustion gas.

Further, a radially outer end portion 120 of the seal plate 110 isprovided with a projection 122 protruding radially outward. The radiallyouter end portion 120 of the seal plate 110 and the projection 122 aretogether fitted into the outer groove 36 (see FIG. 6) of the blade 22.At this time, the projection 122 of the seal plate 110 abuts on a step(not shown) provided in the outer groove 36 and thereby restrictsmovement of the seal plate 110 in the circumferential direction.

As shown in FIG. 13, an axially downstream end surface 118 of theprojecting part 114 is formed along a plane perpendicular to the axialdirection. Further, as shown in FIG. 12, the projecting part 114protrudes downstream in the axial direction from the plate part 72 overa range W3 which is 80% or more of an existence range W2 where the sealplate 44 exists in the circumferential direction. In the embodimentshown in FIG. 12, the projecting part 114 protrudes downstream uniformlyover the entire circumferential range W3 except for a range where thestepped portion is formed on one circumferential side of the downstreamsurface of the seal plate 110.

As shown in FIG. 13, the plate part 112 of the seal plate 110 includestwo or more portions having different thicknesses. In the illustratedembodiment, the thickness t3 of the radially inner end portion 124 ofthe plate part 112 is equal to the thickness t1, and the thickness t4 ofa portion 126 of the plate part 112 between the radially inner endportion 124 and the accommodation chamber forming part 76 is equal tothe thickness t2. Further, the protrusion amount H2 of the projectingpart 114 from the plate part in the axial direction is equal to theprotrusion amount H1 (see FIG. 10) of the accommodation chamber formingpart of the seal plate from the plate part in the axial direction.

As shown in FIG. 14, the plurality of seal plate assemblies 42 includestwo or more seal plate assemblies 42 which are adjacent to each other inthe circumferential direction. Further, the plurality of seal plateassemblies 42 includes a plurality of seal plate assemblies 42 arrangedsymmetrically with respect to the rotation center O of the rotor disc18.

In the illustrated exemplary embodiment, the plurality of seal plateassemblies 42 includes three seal plate assemblies 42 which are adjacentin the circumferential direction and other three seal plate assemblies42 which are symmetrical to the former three seal plate assemblies 42with respect to the rotation center O. Further, in an angular rangewhere the six seal plate assemblies 42 are not disposed in thecircumferential direction, a plurality of seal plates 110 not providedwith the seal plate restraint part 46 are arranged in thecircumferential direction. Although the seal plate 44 provided with theseal plate restraint part 46 differs from the seal plates 110 notprovided with the seal plate restraint part 46 in radial dimension of aportion of the seal plate except the projection, locking plates 56 forholding the seal plate 44 and the seal plate 110 may have the sameshape, and locking pieces 58 configured to press the respective lockingplates toward the end surface 54 of the rotor disc 18 may have the sameshape.

(Method for Disassembling Gas Turbine)

A method for disassembling/assembling the gas turbine 2 having the aboveconfiguration (method for disassembling or assembling gas turbine) willnow be described. Firstly, the method for disassembling the gas turbine2 will be described. The gas turbine 2 is disassembled, for instance, atthe time of maintenance.

First, as shown by arrow a1 in FIG. 15, a jig (not shown) is engagedwith the jig engagement portion 92 of the seal plate restraint part 46through the clearance 38 from the upstream side in the axial direction.Then, the seal plate restraint part 46 is rotated and screwed by the jigto move the seal plate restraint part 46 downstream along the axialdirection. That is, the seal plate restraint part 46 is moved relativeto the seal plate 44. Thereby, a seal plate restraint state (see FIG.15) where at least a part of the seal plate restraint part 46 protrudesupstream in the axial direction from the seal plate 44 and therebyrestricts movement of the seal plate 44 in the radial direction isswitched to a seal plate non-restraint state (see FIG. 16) where theseal plate restraint part 46 does not restrict movement of the sealplate 44 in the radial direction (seal-plate-restraint-state switchingstep).

In the seal-plate-restraint-state switching step, by moving the sealplate restraint part 46 downstream in the axial direction, an engagementstate (see FIG. 15) where the seal plate restraint part 46 engages withthe outer peripheral surface 24 of the rotor disc 18 is switched to anon-engagement state (see FIG. 16) where the seal plate restraint part46 does not engage with the outer peripheral surface 24 of the rotordisc 18, thus switching between the seal plate restraint state and theseal plate non-restraint state. That is, in theseal-plate-restraint-state switching step, the seal plate restraint part46 is moved from a position (see FIG. 15) where the seal plate restraintpart 46 and the outer peripheral surface 24 of the rotor disc 18 overlapin the axial direction to a position (see FIG. 16) where the seal platerestraint part 46 and the outer peripheral surface 24 of the rotor disc18 do not overlap in the axial direction to switch between the sealplate restraint state and the seal plate non-restraint state.

Next, a jig is engaged with the jig engagement recess 108 (see FIG. 8)of the seal plate 44 from the upstream side in the axial direction.Then, as shown by arrow a2 in FIG. 16, the seal plate 44 is pushed downand moved radially inward by the jig to release engagement between theradially outer end portion 48 of the seal plate 44 and the outer groove36 of the blade 22. Thereby, a blade restraint state (see FIG. 16) wherethe seal plate 44 restricts movement of the blade 22 along the axialdirection is switched to a blade non-restraint state (see FIG. 17) wherethe seal plate 44 does not restrict movement of the blade 22 along theaxial direction (blade-restraint-state switching step).

Then, as shown by arrow a3 in FIG. 18, the blade 22 is pulled outupstream in the axial direction from the blade groove 26 of the rotordisc 18 to switch from a blade fitting state (see FIG. 3) where theblade root 34 of the blade 22 is fitted in the blade groove 26 of therotor disc 18 to a blade non-fitting state where the blade root 34 ofthe blade 22 is not fitted in the blade groove 26 of the rotor disc 18(blade-fitting-state switching step). By executing the above steps,removal of the blade 22 from the rotor disc 18 is completed.

(Method for Assembling Gas Turbine)

Secondly, the method for assembling the gas turbine 2 will be described.The gas turbine 2 is assembled, for instance, at the time ofmanufacturing the gas turbine 2 or at the time of maintenance. Theprocedure of the method for assembling the gas turbine 2 is reverse tothat of the method for disassembling the gas turbine 2, as describedbelow.

First, as shown by arrow a4 in FIG. 19, the blade root 34 of the blade22 is inserted into the blade groove 26 (see FIG. 3) of the rotor disc18 from the upstream side in the axial direction to switch from theblade non-fitting state where the blade root 34 of the blade 22 is notfitted in the blade groove 26 of the rotor disc 18 to the blade fittingstate where the blade root 34 of the blade 22 is fitted in the bladegroove 26 of the rotor disc 18 (blade-fitting-state switching step).

Next, as shown by arrow a5 in FIG. 20, a jig is engaged with the jigengagement recess 108 (see FIG. 8) of the seal plate 44 through theclearance 38 from the upstream side in the axial direction. Then, asshown by arrow a6, the seal plate 44 is pushed up and moved radiallyoutward by the jig to engage the radially outer end portion 48 of theseal plate 44 with the outer groove 36 of the blade 22. Thereby, theblade non-restraint state (see FIG. 20) where the seal plate 44 does notrestrict movement of the blade 22 along the axial direction is switchedto the blade non-restraint state (see FIG. 21) where the seal plate 44restricts movement of the blade 22 along the axial direction(blade-restraint-state switching step).

Then, a jig (not shown) is engaged with the jig engagement portion 92 ofthe seal plate restraint part 46 from the upstream side in the axialdirection. Then, the seal plate restraint part 46 is rotated by the jigto move the seal plate restraint part 46 upstream along the axialdirection. Thereby, the seal plate non-restraint state (see FIG. 21)where the seal plate restraint part 46 does not restrict movement of theseal plate 44 in the radial direction is switched to the seal platerestraint state (see FIG. 22) where at least a part of the seal platerestraint part 46 protrudes upstream in the axial direction from theseal plate 44 and thereby restricts movement of the seal plate 44 in theradial direction (seal-plate-restraint-state switching step).

In the seal-plate-restraint-state switching step, by moving the sealplate restraint part 46 upstream in the axial direction, thenon-engagement state (see FIG. 21) where the seal plate restraint part46 does not engage with the rotor disc 18 is switched to the engagementstate (see FIG. 22) where the seal plate restraint part 46 engages withthe rotor disc 18, thus switching from the seal plate non-restraintstate to the seal plate restraint state. That is, in theseal-plate-restraint-state switching step, the seal plate restraint part46 is moved from a position (see FIG. 21) where the seal plate restraintpart 46 and the rotor disc 18 do not overlap in the axial direction to aposition (see FIG. 22) where the seal plate restraint part 46 and therotor disc 18 overlap in the axial direction to switch from the sealplate non-restraint state to the seal plate restraint state. Byexecuting the above steps, attachment of the blade 22 to the rotor disc18 is completed.

Thirdly, some advantages obtainable from the above method fordisassembling/assembling the gas turbine 2 will be described.

As described with reference to FIGS. 15, 16, 21, and 22, in theseal-plate-restraint-state switching step, the seal plate non-restraintstate and the seal plate restraint state are switched by operating theseal plate restraint part 46 from the upstream side in the axialdirection, i.e., from a side on which the seal plate restraint part 46protrudes from the seal plate 44 (side closer to the rotor disc 18 thanthe seal plate 44 is in axial direction).

Thus, it is possible to switch between the seal plate restraint stateand the seal plate non-restraint state from the opposite side of therotor disc 18 from the seal plate 44, while visually recognizing whetherthe seal plate restraint part 46 is in the seal plate restraint state orthe seal plate non-restraint state, when disassembling or assembling thegas turbine 2. Thus, it is easy to appropriately switch between the sealplate restraint state and the seal plate non-restraint state from theopposite side of the rotor disc 18 from the seal plate 44.

Thus, it is easy to appropriately switch between the engagement stateand the non-engagement state between the seal plate 44 and the blade 22from the opposite side of the rotor disc 18 from the seal plate 44, whendisassembling or assembling the gas turbine 2.

In particular, in a case where a casing of the gas turbine 2 has anopening (e.g., opening for attaching combustor 6 or entrance foroperators) on the upstream side of the rotor disc 18, it is possible toattach or remove the blade 22 with respect to the rotor disc 18, withoutremoving the casing 10 of the gas turbine 2, from the upstream side ofthe rotor disc 18. Thus, it is possible to improve maintenanceperformance of the gas turbine 2.

Further, in the seal-plate-restraint-state switching step in the methodfor disassembling/assembling the gas turbine 2, the seal plate restraintstate and the seal plate non-restraint state are switched by moving theseal plate restraint part 46 along the axial direction.

Thus, for instance, even if force acts on the seal plate restraint part46 in a direction different from the axial direction of the seal platerestraint part 46 by friction a7 (see FIG. 7) caused between the outerperipheral surface 24 of the rotor disc 18 and the seal plate restraintpart 46 due to vibration during turning (low-speed rotation) of the gasturbine rotor 16, or due to acceleration or deceleration of rotation ofthe rotor disc 18 during turning of the gas turbine rotor 16, the sealplate non-restraint state and the seal plate restraint state are noteasily switched.

Thus, it is possible to control switching between the engagement stateand the non-engagement state between the seal plate 44 and the blade 22at an unintended timing.

Further, in the seal-plate-restraint-state switching step in the methodfor disassembling/assembling the gas turbine 2, the seal plate restraintstate and the seal plate non-restraint state are switched by rotatingthe seal plate restraint part 46 while the male thread 86 (see FIG. 6)provided in the seal plate restraint part 46 is screwed with the femalethread 84 (see FIG. 6) provided in the seal plate 44.

With the above configuration, since the seal plate non-restraint stateand the seal plate restraint state are switched by rotating the sealplate restraint part 46 while the male thread 86 is screwed with thefemale thread 84, it is possible to easily control the protruding stateof the seal plate restraint part 46. That is, it is possible to controlthe moving amount of the male thread 86 relative to the female thread84, and thus it is possible to prevent the seal plate restraint part 46from protruding unintentionally. Thus, it is possible to enhance theeffect of controlling switching between the engagement state and thenon-engagement state between the seal plate 44 and the blade 22 at anunintended timing. Further, since the seal plate non-restraint state andthe seal plate restraint state are not switched unless the seal platerestraint part 46 is rotated, it is possible to move the seal plate 44in the radial direction smoothly and easily while keeping the seal platenon-restraint state, for instance.

When the gas turbine rotor 16 is rotating at high rotational speed, theseal plate 44 is held to the outer groove 36 by centrifugal force, andthus the seal plate restraint part 46 is not in contact with the outerperipheral surface 24 of the rotor disc. However, when the gas turbinerotor 16 is turning, the seal plate 44 moves radially inward due to itsown weight, and the seal plate restraint part 46 comes into contact withthe outer peripheral surface 24. At this time, the seal plate restraintpart 46 intends to rotate in a direction opposite to the rotationaldirection of the gas turbine rotor 16 due to friction.

Accordingly, the male thread 86 and the female thread 84 are threaded soas to rotate in a direction in which the seal plate restraint part 46protrudes when they receive friction from the outer peripheral surface24 of the rotor disc 18 during turning of the gas turbine rotor 16. Forinstance, in a case where the rotational direction of the gas turbinerotor 16 is counterclockwise in the upstream view, the male thread 86and the female thread 84 are threaded so as to rotate in a direction inwhich the seal plate restraint part 46 protrudes upstream in the axialdirection when the seal plate restraint part 46 intends to rotateclockwise in the upstream view.

Further, in the seal-plate-restraint-state switching step in the methodfor disassembling/assembling the gas turbine 2, the seal plate restraintstate and the seal plate non-restraint state are switched by moving theseal plate restraint part 46 along the axial direction against a biasingforce of the biasing part 94 (see FIG. 6) biasing the seal platerestraint part 46.

Accordingly, even if a weaker force than the biasing force of thebiasing part acts on the seal plate restraint part 46, the seal platerestraint state is not switched to the seal plate non-restraint state.Thus, it is possible to enhance the effect of controlling switchingbetween the engagement state and the non-engagement state between theseal plate 44 and the blade 22 at an unintended timing.

Further, the biasing force of the biasing part 94 reduces loosening ofthe thread 86. Thus, also for this reason, it is possible to enhance theeffect of controlling switching between the engagement state and thenon-engagement state between the seal plate 44 and the blade 22 at anunintended timing.

Further, in the seal-plate-restraint-state switching step, as shown inFIGS. 7, 15, and 21, the seal plate restraint state and the seal platenon-restraint state are switched by operating the seal plate restraintpart 46 from the upstream side in the axial direction, via the clearance38 between the platform 30 of the blade 22 and the region 128 on theouter peripheral surface 24 of the rotor disc 18 except the blade groove26 for receiving the blade 22. In this case, the seal plate restraintstate and the seal plate non-restraint state are switched by operatingthe seal plate restraint part 46 through a space between two adjacentblades 22 on the radially inner side of the platforms of the two blades22.

With this method, it is possible to easily switch between the engagementstate and the non-engagement state between the seal plate and the blade.The reasons will now be described.

The resonance of the blade 22 can be avoided by adjusting the naturalfrequency of the blade 22 through adjustment of the length of the shank32 between the platform 30 and the blade root 34 of the blade 22.Further, the shape and the size of the blade root 34 of the blade 22 aredetermined based on required strength. Meanwhile, it is not preferableto increase the outer diameter of the rotor disc 18 larger thannecessary, in view of suppressing the increase in centrifugal force ofthe rotor disc 18.

Accordingly, in case of adopting a configuration which suppresses theincrease in centrifugal force of the rotor disc 18 while avoiding theresonance of the blade 22, a wide clearance 38 is likely to be formedbetween the platform 30 of the blade 22 and the region 128 on the outerperipheral surface 24 of the rotor disc 18 except the blade groove 26for receiving the blade 22.

Thus, it is possible to operate the seal plate restraint part 46 via thewide clearance 38 to switch between the seal plate non-restraint stateand the seal plate restraint state, which facilitates the switching.Consequently, it is possible to easily switch between the engagementstate and the non-engagement state between the seal plate and the blade.

(Modification of Seal Plate Assembly)

Next, modifications according to some embodiments will be described.Seal plate assemblies 42(42B to 42K, M) according to the followingmodifications differ from the above-described seal plate assembly42(42A) in the configuration for switching between the seal platenon-restraint state and the seal plate restraint state. In the followingmodifications, elements having the same functions as those in the aboveembodiments are denoted by the same reference signs, and descriptionthereof will be omitted. The characteristic features of eachmodification will be mainly described below.

FIG. 23 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42B)according to an embodiment, taken along the axial direction.

In the seal plate assembly 42(42A) shown in FIG. 6, the cylindrical part82 having the female thread 84 is included in the accommodation chamberforming part 76 of the seal plate 44, while the male thread 86 screwedwith the female thread 84 is included in the seal plate restraint part46. By contrast, in the seal plate assembly 42(42B) shown in FIG. 23,the cylindrical part 82 having the female thread 84 is included in theseal plate restraint part 46, while the male thread 86 screwed with thefemale thread 84 is included in the accommodation chamber forming part76 of the seal plate 44.

The above configuration also enables operation on the upstream side inthe axial direction to rotate the seal plate restraint part 46 andthereby move the seal plate restraint part 46 along the axial direction,as in the seal-plate-restraint-state switching step described above.Thereby, it is possible to switch between the seal plate non-restraintstate where the seal plate restraint part 46 does not restrict movementof the seal plate 44 in the radial direction and the seal platerestraint state where at least a part of the seal plate restraint part46 protrudes upstream in the axial direction from the seal plate 44 andthereby restricts movement of the seal plate 44 in the radial direction.

FIG. 24 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42C)according to an embodiment, taken along the axial direction.

In the seal plate assembly 42 shown in FIG. 24, as in the embodimentshown in FIG. 23, the cylindrical part 82 having the female thread 84 isincluded in the seal plate restraint part 46, while the male thread 86screwed with the female thread 84 is included in the accommodationchamber forming part 76 of the seal plate 44. The outer peripheralsurface of the cylindrical part 82 is provided with a brim part 88protruding outward in the radial direction of the female thread 84, anda Nord-Lock washer 130 is disposed between the brim part 88 and a brimrestraint part 96 of the accommodation chamber forming part 76.

The above configuration also enables operation on the upstream side inthe axial direction to rotate the seal plate restraint part 46 andthereby move the seal plate restraint part 46 along the axial direction,as in the seal-plate-restraint-state switching step described above.Thereby, it is possible to switch between the seal plate non-restraintstate where the seal plate restraint part 46 does not restrict movementof the seal plate 44 in the radial direction and the seal platerestraint state where at least a part of the seal plate restraint part46 protrudes upstream in the axial direction from the seal plate 44 andthereby restricts movement of the seal plate 44 in the radial direction.

Further, with the above configuration, since the Nord-Lock washer 130serves to restrict rotation of the seal plate restraint part 46, it ispossible to control switching between the seal plate restraint state andthe seal plate non-restraint state at an unintended timing.

FIG. 25 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42D)according to an embodiment, taken along the axial direction.

In the embodiment shown in FIG. 25, the seal plate assembly 42 includesa seal plate restraint part 46 formed as a cylindrical member 85 havinga closed axially upstream end, and a biasing part 94 biasing the sealplate restraint part 46 upstream in the axial direction. In theillustrated embodiment, the biasing part 94 is configured as a coilspring. The biasing part 94 is supported by a strut 132 protruding inthe axial direction from the wall part 80 on the downstream side of theaccommodation chamber forming part 76 of the seal plate 44. The sealplate assembly 42(42D) has a simpler structure than the seal plateassembly 42(42A to 42C) in that a thread mechanism is not provided inthe seal plate restraint part 46 and in the seal plate 44.

In the seal plate assembly 42(42D), as shown in FIGS. 25 and 26, bypushing an axially upstream end surface 134 of the seal plate restraintpart 46 downstream in the axial direction against the biasing force ofthe biasing part 94, the seal plate restraint part 46 can be moveddownstream along the axial direction. Thereby, it is possible to switchfrom the seal plate restraint state (see FIG. 25) where at least a partof the seal plate restraint part 46 protrudes in the axial directionfrom the seal plate 44 and thereby restricts movement of the seal plate44 in the radial direction to the seal plate non-restraint state (seeFIG. 26) where the seal plate restraint part 46 does not restrictmovement of the seal plate 44 in the radial direction.

In the embodiment shown in FIGS. 25 and 26, in contract to theabove-described seal plate assemblies 42(42A to 42C), a thread mechanismis not provided in the seal plate restraint part. Therefore, it isnecessary to impart a downstream force to the seal plate restraint part46 in order to keep the seal plate non-restraint state. Accordingly, inthe blade-restraint-state switching step, while pushing the upstream endsurface 134 of the seal plate restraint part 46 in the downstreamdirection to keep the seal plate non-restraint state, a jig is engagedwith the jig engagement recess 108 (see FIG. 8) formed in the seal plate44, and the seal plate 44 is moved in the radial direction. Thereby, theblade restraint state can be switched to the blade non-restraint state.

FIG. 27 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42E)according to an embodiment, taken along the axial direction.

42(42E) shown in FIG. 27 includes a seal plate restraint part 46configured as a pin 93 and a biasing part 94 configured as a coilspring. The seal plate restraint part 46 includes a compressionrestriction part 136 disposed on a downstream end in the axialdirection, a brim part 88 protruding radially outward from thecompression restriction part 136, and a protruding part 90 protrudingupstream in the axial direction from the brim part 88. The biasing part94 is configured to bias the brim part 88 upstream. The accommodationchamber forming part 76 has a facing part 138 which faces thecompression restriction part 136 in the axial direction. The compressionrestriction part 136 is configured to come into contact with the facingpart 138, and this contact restricts axially downstream movement of theseal plate restraint part 46, thereby preventing excessive compressionof the biasing part 94. The seal plate assembly 42(42E) has a simplerstructure than the seal plate assembly 42(42A to 42C) in that a threadmechanism is not provided in the seal plate restraint part 46 and in theseal plate 44.

In the seal plate assembly 42(42E), as shown in FIGS. 27 and 28, bypushing an axially upstream end surface 194 of the seal plate restraintpart 46 downstream in the axial direction, the seal plate restraint part46 can be moved downstream along the axial direction, as in the sealplate assembly 42(42E). Thereby, it is possible to switch from the sealplate restraint state (see FIG. 27) where at least a part of the sealplate restraint part 46 protrudes upstream in the axial direction fromthe seal plate 44 and thereby restricts movement of the seal plate 44 inthe radial direction to the seal plate non-restraint state (see FIG. 28)where the seal plate restraint part 46 does not restrict movement of theseal plate 44 in the radial direction. Further, theblade-restraint-state switching step can also be performed in the sameway as in the seal plate assembly 42(42E).

FIG. 29 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42F)according to an embodiment, taken along the axial direction.

In the embodiment shown in FIG. 29, the seal plate 44 and the seal platerestraint part 46 are formed integrally. The seal plate restraint part46 is formed as a branch part 97 diverging from a body part 95 of theseal plate 44, and protrudes upstream in the axial direction and inwardin the radial direction from the body part 95 in the seal platerestraint state. This seal plate assembly 42 has a simpler structurethan the seal plate assemblies 42(42A to 42E) in that it does notinclude the biasing part and the thread mechanism.

In this seal plate assembly 42, as shown in FIGS. 29 and 30, by pushingan end surface 196 of the seal plate restraint part 46 from the upstreamside in the axial direction to plastically deform the seal platerestraint part 46 downstream in the axial direction, it is possible toswitch from the seal plate restraint state (see FIG. 29) where at leasta part of the seal plate restraint part 46 protrudes upstream in theaxial direction from the seal plate 44 and thereby restricts movement ofthe seal plate 44 in the radial direction to the seal platenon-restraint state (see FIG. 30) where the seal plate restraint part 46does not restrict movement of the seal plate 44 in the radial direction.Further, by pulling the seal plate restraint part 46 from the upstreamside in the axial direction to plastically deform the seal platerestraint part 46 upstream in the axial direction, it is possible toswitch from the seal plate non-restraint state (see FIG. 30) where theseal plate restraint part 46 does not restrict movement of the sealplate 44 in the radial direction to the seal plate restraint state (FIG.29) where at least a part of the seal plate restraint part 46 protrudesupstream in the axial direction from the seal plate 44 and therebyrestricts movement of the seal plate 44 in the radial direction.

FIG. 31 is an enlarged cross-sectional view of the vicinity of a sealplate restraint part 46 (movable part) of a seal plate assembly 42(42G)according to an embodiment, taken along the axial direction.

In the embodiment shown in FIG. 31, the seal plate 44 includes a femalethread 142 provided in a through hole 140 which penetrates the sealplate 44 in the axial direction, and the seal plate restraint part 46 isconfigured as a male thread (screw) 144 screwed with the female thread142. The male thread 144 has an axial length longer than that of thefemale thread 142. The leading end (axially upstream end) of the malethread 144 is provided with a jig engagement portion 92 capable ofengaging with a jig for rotating the male thread. Further, the sealplate assembly 42(42G) includes a washer 146 disposed between the headof the male thread 144 and the seal plate 44.

With the above configuration, by screwing the male thread 144 into thefemale thread 142 from the downstream side in the axial direction, themale thread 144 penetrates the seal plate 44 and the leading end of themale thread 144 protrudes upstream in the axial direction from the sealplate 44. The seal plate 44 has a receiving part 148 for preventing themale thread 144 from falling from the seal plate 44 on the downstreamside in the axial direction. The receiving part 148 has an L-shapedcross-section composed of a protruding portion protruding downstream inthe axial direction from a position of the seal plate 44 more radiallyinward than the through hole 140 and an extending portion extendingradially outward from the downstream end of the protruding portion. Thisseal plate assembly 42 has a simpler structure than some seal plateassemblies 42(42A, 42B, 42D, 42E) described above in that it does notinclude the biasing part.

In this seal plate assembly 42, by operating the jig engagement portion92 of the male thread 144 from the upstream side in the axial directionto rotate the male thread 144, the male thread 144 can be moved alongthe axial direction. Thereby, it is possible to switch between the sealplate non-restraint state (see FIG. 32) where the male thread 144 doesnot restrict movement of the seal plate 44 in the radial direction andthe seal plate restraint state (see FIG. 31) where at least a part ofthe male thread 144 protrudes in the axial direction from the seal plate44 and thereby restricts movement of the seal plate 44 in the radialdirection.

The above-described seal plate assemblies 42(42A to 42G) according tosome embodiments switch between a state where the seal plate restraintpart 46 does not engage with the rotor disc 18 and a state where theseal plate restraint part 46 engages with the rotor disc 18 by movingthe seal plate restraint part 46 along the axial direction, therebyenabling switching between the seal plate restraint state and the sealplate non-restraint state.

In contrast to them, the following seal plate assemblies 42 according tosome embodiments switch between a state where the seal plate restraintpart 46 does not engage with the seal plate 44 and a state where theseal plate restraint part 46 engages with the seal plate 44 by movingthe seal plate restraint part 46 along the axial direction, therebyenabling switching between the seal plate restraint state and the sealplate non-restraint state.

FIG. 33 is a diagram for describing the configuration of a seal plateassembly 42(42H) according to an embodiment, which shows a partialcross-section of the gas turbine rotor 16 taken along the axialdirection.

The seal plate assembly shown in FIG. 33 includes a seal plate 44 and aseal plate restraint part 46 configured as a seal plate fall preventionpiece 180 (recess engagement member). The seal plate 44 has a firstsurface 50 and a second surface 52 which face in opposite directions, asin the above embodiments. The first surface 50 faces upstream in theaxial direction, while the second surface 52 faces downstream in theaxial direction.

In the embodiment shown in FIG. 33, a recess 150 is formed in the firstsurface 50. The seal plate restraint part 46 is mounted in the recess150 of the seal plate 44. The size of the seal plate restraint part 46in the axial direction is larger than the depth of the recess 150 in theaxial direction. Thus, in a state where the seal plate restraint part 46is mounted in the recess 150, at least a part of the seal platerestraint part 46 protrudes in the axial direction from the seal plate44 and thereby enables restriction of movement of the seal plate 44 inthe radial direction.

With the above configuration, by removing the seal plate restraint part46 mounted in the recess 150 of the seal plate 44 from the recess 150,or by mounting the seal plate restraint part 46 in the recess 150, it ispossible to switch between the seal plate non-restraint state (see FIG.34) and the seal plate restraint state (see FIG. 33). That is, a statewhere the seal plate restraint part 46 does not engage with the sealplate 44 and a state where the seal plate restraint part 46 engages withthe seal plate 44 are switched by moving the seal plate restraint part46 along the axial direction, thereby switching between the seal platerestraint state and the seal plate non-restraint state. Further, theseal plate assembly 42(42H) makes it possible to shorten the length ofthe seal plate 44 in the radial direction, compared to otherembodiments, for instance, the seal plate assembly 42(42A). Further, thelength of the locking plate 56 in the radial direction may be changed asappropriate.

In addition, as shown in FIG. 35, two or more seal plate restraint parts46 may be mounted on the seal plate 44. In the embodiment shown in FIG.35, each seal plate restraint part 46 is disposed so as to overlap theclearance 38 when viewed in the axial direction. Further, while, in theillustrated embodiment, the recess 150 is disposed in the vicinity ofthe center of the first surface 50 of the seal plate 44 in the radialdirection, it is not limited thereto. The recess 150 may be disposed ina radially inner end of the first surface 50 of the seal plate 44, forinstance.

FIG. 36 is a diagram for describing the configuration of a seal plateassembly 42(42I) according to an embodiment, which shows a partialcross-section of the gas turbine rotor 16 taken along the axialdirection.

In the embodiment shown in FIG. 36, the rotor disc 18 includes aprojecting part 152 protruding radially outward along the first surface50 of the seal plate 44. The projecting part 152 is provided with athrough hole 154 penetrating in the axial direction, and a female thread156 is formed in the through hole 154. The seal plate restraint part 46of the seal plate assembly 42(42I) includes a male thread 158 configuredto be inserted into the through hole 154 and screw with the femalethread 156. An axially downstream end portion of the seal platerestraint part 46 engages with the recess 150 formed in the firstsurface 50 of the seal plate 44.

With the above configuration, by rotating and moving the seal platerestraint part 46 in the axial direction while the male thread 158provided in the seal plate restraint part 46 is screwed with the femalethread 156 provided in the rotor disc 18, it is possible to switchbetween the seal plate non-restraint state (see FIG. 37) where the sealplate restraint part 46 does not restrict movement of the seal plate 44in the radial direction and the seal plate restraint state (FIG. 36)where at least a part of the seal plate restraint part 46 protrudes inthe axial direction from the seal plate 44 and thereby restrictsmovement of the seal plate 44 in the radial direction.

FIG. 38 is a diagram for describing the configuration of a seal plateassembly 42(42J) according to an embodiment, which shows a partialcross-section of the gas turbine rotor 16 taken along the axialdirection.

The seal plate assembly 42 shown in FIG. 38 includes a seal plate 44 anda seal plate restraint part 46 configured as a seal plate fallprevention pin 182 (recess engagement member). The seal plate 44 has afirst surface 50 and a second surface 52 which face in oppositedirections, as in the above embodiments. The first surface 50 facesupstream in the axial direction, while the second surface 52 facesdownstream in the axial direction.

In the embodiment shown in FIG. 38, a recess 150 is formed in the firstsurface 50. Further, the rotor disc 18 has a through hole 160penetrating in the axial direction (direction perpendicular to firstsurface 50). The seal plate fall prevention pin 182 is inserted into thethrough hole 160 and extends in the axial direction, and the leading endof the seal plate fall prevention pin 182 engages with the recess 150.The through hole 160 is provided with a stepped portion. A steppedportion 162 formed in the seal plate fall prevention pin 182 abuts onthe stepped portion of the through hole 160, thereby determining theposition of the seal plate fall prevention pin 182 in the axialdirection. In the seal plate restraint state, while the stepped portion162 of the seal plate fall prevention pin 182 abuts on the steppedportion of the through hole 160, the leading end of the seal plate fallprevention pin 182 engages with the recess 150 as described above.Further, a fall prevention pin cap 164 for preventing axially upstreammovement of the seal plate fall prevention pin 182 is disposed on theaxially upstream side of the seal plate fall prevention pin 182.

In the embodiment shown in FIGS. 38 and 39, the region 128 on the outerperipheral surface 24 of the rotor disc 18 includes a thickened portion166 extending in the axial direction, and the through hole 160 is formedin the thickened portion 166. In the illustrated embodiment, the sealplate fall prevention pin 182 has a circular cross-sectional shape.

With the above configuration, by operating the seal plate fallprevention pin 182 via the through hole 160 to move the seal plate fallprevention pin 182 in the axial direction with the fall prevention pincap 164 being detached, it is possible to switch between a state wherethe leading end of the seal plate fall prevention pin 182 does notengage with the recess 150 of the seal plate 44 and a state where theleading end of the seal plate fall prevention pin 182 engages with therecess 150 of the seal plate 44. Thereby, it is possible to switchbetween the seal plate non-restraint state (see FIG. 40) and the sealplate restraint state (see FIG. 38).

As shown in FIGS. 41 and 42, the seal plate fall prevention pin 182 maybe inserted into a pin groove part 168 formed in the region 128 on theouter peripheral surface 24 of the rotor disc 18 along the axialdirection. In the embodiment shown in FIGS. 41 and 42, the pin groovepart 168 has a retaining portion 170 configured to prevent the sealplate fall prevention pin 182 from falling out from the pin groove part168 radially outward. In the illustrated embodiment, the seal plate fallprevention pin 182 has a rectangular cross-sectional shape.

With the above configuration, similarly, by moving the seal plate fallprevention pin 182 in the axial direction, it is possible to switchbetween a state where the leading end of the seal plate fall preventionpin 182 does not engage with the recess 150 of the seal plate 44 and astate where the leading end of the seal plate fall prevention pin 182engages with the recess 150 of the seal plate 44. Thereby, it ispossible to switch between the seal plate non-restraint state (see FIG.42) and the seal plate restraint state (see FIG. 41).

FIG. 43 is a diagram for describing the configuration of a seal plateassembly 42(42M) according to an embodiment, which shows a partialcross-section of the gas turbine rotor 16 taken along the axialdirection.

The seal plate assembly 42 shown in FIG. 31 has been described as theembodiment configured so that the leading end of the male thread 144serving as the seal plate restraint part 46 is capable of protrudingupstream in the axial direction from the seal plate 44. In contract tothis embodiment, the seal plate assembly 42 shown in FIG. 43 isconfigured so that the male thread 144 serving as the seal platerestraint part 46 is capable of protruding downstream in the axialdirection from the seal plate 44. In this case, the gas turbine rotor 16includes a support part 192 disposed downstream of the seal plate in theaxial direction and configured to engage with the male thread 144. Withthe above configuration, by moving the male thread 144 along the axialdirection to switch between a state where the male thread 144 does notengage with the support part 192 and a state where the male thread 144engages with the support part 192, the seal plate non-restraint state(see FIG. 44) and the seal plate restraint state (see FIG. 43) areswitched. The support part 192 may be a part of the rotor disc 18 or maybe disposed on the rotational axis of the gas turbine rotor 16separately from the rotor disc 18.

In the seal plate assembly 42(42M), by operating the jig engagementportion 92 of the male thread 144 from the upstream side in the axialdirection to rotate the male thread 144 and move the male thread 144along the axial direction, it is possible to switch between the sealplate non-restraint state where the male thread 144 does not restrictmovement of the seal plate 44 in the radial direction and the seal platerestraint state where at least a part of the male thread 144 protrudesdownstream in the axial direction from the seal plate 44 and therebyrestricts movement of the seal plate 44 in the radial direction.

Although, in the above-described embodiments, the position of the sealplate restraint part 46 as viewed in the axial direction has beendescribed with the drawings only for the seal plate assemblies 42(42A,42G), also in the other seal plate assemblies 42(42B to 42F, 42H, 42I,42K, M), the seal plate restraint part 46 is positioned so as to overlapthe clearance 38 when viewed in the axial direction.

Thus, it is possible to operate the seal plate restraint part 46 via thewide clearance 38 to switch between the seal plate non-restraint stateand the seal plate restraint state, which facilitates the switching.Consequently, it is possible to easily switch between the engagementstate and the non-engagement state between the seal plate and the blade.

FIG. 45 is a plan view showing a configuration example of an inspectiondevice for identifying the assembly state of the seal plate assembly 42(which shows a partial cross-section in the vicinity of a holding hole522 of an inspection rod holder 520). FIG. 46 is a diagram of aninspection device viewed from upstream in the insertion direction of aninspection rod. FIG. 47 is a diagram showing a usage state of thedetection device shown in FIGS. 45 and 46.

The inspection device 500 shown in FIGS. 45 and 46 is used to checkappropriateness of the assembly state of the seal plate assembly 42 bymeasuring whether the protrusion amount of the seal plate restraint part46 of the seal plate assembly 42 from the seal plate 44 is within apredetermined range, as shown in FIG. 47.

The inspection device 500 is useful when it is difficult to directlymeasure the protrusion amount of the seal plate restraint part 46, andthe inspection device 500 can be used for the seal plate assemblies42(42A to 42I), for instance. Although, in the example shown in FIG. 47,the inspection target is the seal plate assembly 42(42A to 42H)including the seal plate restraint part 46 engaging with the outerperipheral surface 24 of the rotor disc 18, the seal plate assembly 42Ican also be inspected by the inspection device 500. In a case where adistal end portion 516 of an inspection rod 510 described later isconfigured to come into contact with the seal plate restraint part 46 inthe through hole 140 of the seal plate 44 of the seal plate assembly42M, the seal plate assembly 42M can also be inspected by the inspectiondevice 500.

In some embodiments, as shown in FIGS. 45 and 46, the inspection device500 includes an inspection rod 510 and an inspection rod holder 520 forholding the inspection rod 510 in a predetermined orientation.

The inspection rod 510 is movable in a longitudinal direction of theinspection rod 510 relative to the inspection rod holder 520 in a statewhere the inspection rod 510 is restrained by the inspection rod holder520 in a predetermined orientation. The inspection rod 510 is anelongated member longer than the clearance 38 between the shanks 32 oftwo circumferentially adjacent blades 22 and having a cross-sectionalshape to pass through the clearance 38.

A proximal end portion 512 of the inspection rod 510 has at least onemeasurement surface 514(514A, 514B). The measurement surface 514 is usedfor determining whether the insertion depth of the inspection rod 510into the inspection rod holder 520 is within a predetermined rangeduring use of the inspection device 500, as described later in detail.

In the exemplary embodiment shown in FIG. 45, a pair of measurementsurfaces 514A, 514B is disposed on both sides of the central axis Z ofthe inspection rod 510. The measurement surfaces 514A, 514B are locatedat different positions in the longitudinal direction of the inspectionrod 510. A distance AZ between the measurement surfaces 514A and 514B isset to be smaller than (e.g., 0.5 times or less) the protrusion lengthof the seal plate restraint part 46 when the seal plate assembly 42(42Ato 42H) is in the appropriate assembly state (i.e., length of engagementbetween seal plate restraint part 46 and outer peripheral surface 24 ofrotor disc 18).

A distal end portion 516 of the inspection rod 510 is a portion whichcomes into contact with the seal plate restraint part 46 during use ofthe inspection device 500. The distal end portion 516 may be configuredto be insertable into a recess (not shown in FIG. 47) provided in theseal plate restraint part 46. In this case, the distal end portion 516of the inspection rod 510 is easily brought into contact with apredetermined portion in the recess of the seal plate restraint part 46during use of the inspection device 500, and thus it is possible toimprove the reliability of inspection.

The recess of the seal plate restraint part 46 may be the jig engagementportion 92.

The inspection rod 510 includes an enlarged diameter part 518, disposedon the distal end side of the measurement surface 514, for engaging withan enlarged diameter portion 522A of the holding hole 522. During use ofthe inspection device 500, the enlarged diameter part 518 of theinspection rod 510 is fitted into the enlarged diameter portion 522A ofthe holding hole 522, so that the orientation of the inspection rod 510is restricted. Thus, it is possible to perform stable inspection withthe inspection device 500.

On the other hand, the inspection rod holder 520 has the holding hole522 for holding the inspection rod 510, and an axial-directionpositioning surface 524 for determining the position of the inspectionrod holder 520 with respect to the axial direction of the gas turbine 2during use of the inspection device 500.

In the exemplary embodiment shown in FIG. 45, the axial-directionpositioning surface 524 abuts on an axial-direction reference surface600 (see FIG. 47) during use of the inspection device 500, and therebyenabling positioning of the inspection rod holder 520 with respect tothe axial direction. The axial-direction reference surface 600 may be anaxial end surface of the rotor disc 18 as in the example shown in FIG.47, or may be an axial end surface of the shank 32 or the blade root 34of the blade 22.

Further, the inspection rod holder 520 may include, in addition to theaxial-direction positioning surface 524, a radial-direction positioningsurface 526 which abuts on a radial-direction reference surface 610during use of the inspection device 500 for positioning of theinspection rod holder 520 with respect to the radial direction. In theexample shown in FIG. 47, the radial-direction reference surface 610 isprovided on the rotor disc 18.

The radial-direction positioning surface 526 of the inspection rodholder 520 may have a shape corresponding to the radial-directionreference surface 610. In the example shown in FIG. 46, theradial-direction positioning surface 526 has an arc shape when viewedfrom upstream in the insertion direction of the inspection rod 510.

The inspection rod holder 520 has a measurement reference surface 528 inthe vicinity of the opening of the holding hole 522. The measurementreference surface 528 is a surface serving as a reference to be comparedwith the position of the measurement surface 514(514A, 514B) of theinspection rod 510 during use of the inspection device 500.

In the example shown in FIG. 45, the measurement reference surface 528is provided, in the vicinity of the holding hole 522, at an end surfaceof the inspection rod holder 520 opposite the axial-directionpositioning surface 524, as a flat surface perpendicular to the axialdirection of the holding hole 522. The example shown in FIGS. 45 to 47is designed assuming that the clearance 38 between the shanks 32 ofcircumferentially adjacent blades 22 extends obliquely with respect tothe axial direction of the gas turbine 2, and thus the measurementreference surface 528 and the axial-direction positioning surface 524are not parallel to each other but titled at an inclination angle.However, it is not limited to this example.

When using the inspection device 500 with the above configuration, asshown in FIG. 47, first, the axial-direction positioning surface 524 andthe radial-direction positioning surface 526 of the inspection rodholder 520 are brought into contact with the axial-direction referencesurface 600 and the radial-direction reference surface 610,respectively, to determine the position of the inspection rod holder520. Thus, the relative position of the measurement reference surface528 of the inspection rod holder 520 with respect to the seal plateassembly 42 is determined.

Next, the inspection rod 510 is inserted into the holding hole 522 ofthe inspection rod holder 520, and the inspection rod 510 is pushed intothe holding hole 522 until the distal end portion 516 of the inspectionrod 510 comes into contact with the seal plate restraint part 46 of theseal plate assembly 42 via the clearance 38. When the inspection rod 510is pushed, the enlarged diameter part 518 of the inspection rod 510 isfitted into the enlarged diameter portion 522A of the holding hole 522,so that the orientation of the inspection rod 510 is restricted. Thedistal end portion 516 of the inspection rod 510 may be engaged with therecess (not shown) (e.g., jig engagement portion 92) of the seal platerestraint part 46.

Further, in a state where the inspection rod 510 is inserted and thedistal end portion 516 of the inspection rod 510 is in contact with theseal plate restraint part 46, it is checked whether the assembly stateof the seal plate assembly 42 is appropriate, based on the relativeposition of the measurement surface 514(514A, 54B) of the inspection rod510 with respect to the measurement reference surface 528 of theinspection rod holder 520.

For instance, the position of the measurement reference surface 528 ofthe inspection rod holder 520 may be set to be positioned between thepair of measurement surfaces 514A, 514B of the inspection rod 510 in acase where the assembly state of the seal plate assembly 42 isappropriate. Thereby, it is possible to easily check the appropriatenessof the assembly state of the seal plate assembly 42. That is, if boththe measurement surfaces 514A, 514B are located on a side of themeasurement reference surface 528 on which the seal plate assembly 42 ispositioned (i.e., if both the measurement surfaces 514A, 514B arelocated within the holding hole 522), it is determined that theprotrusion amount of the seal plate restraint part 46 from the sealplate 44 is insufficient, and the seal plate assembly 42 is not in theappropriate assembly state. Conversely, if one measurement surfaces 514Ais located on a side of the measurement reference surface 528 oppositethe side on which the seal plate assembly 42 is positioned (i.e., themeasurement surface 514A is located outside the holding hole 522), andthe other measurement surface 514B is located on the side of themeasurement reference surface 528 on which the seal plate assembly 42 ispositioned (i.e., the measurement surface 514B is located within theholding hole 522), it is determined that the protrusion amount of theseal plate restraint part 46 from the seal plate 44 is within apredetermined range, and the seal plate assembly 42 is in theappropriate assembly state.

Although in the inspection device 500 with the above configuration, theappropriateness of the assembly state of the seal plate assembly 42 isdetermined based on the relative positional relationship between themeasurement surface 514 (514A, 514B) and the measurement referencesurface 528, in other embodiments, the appropriateness of the assemblystate of the seal plate assembly 42 may be determined by comparing amark provided in the inspection rod 510 with the measurement referencesurface 528.

Further, although in the inspection device 500 with the aboveconfiguration, the position of the inspection rod holder 520 is notdetermined with respect to the circumferential direction of the gasturbine 2, in other embodiments, the device may have a function forpositioning the inspection rod holder 520 in the circumferentialdirection. In this case, at least one of the side surfaces of two shanks32 which are adjacent to each other in the circumferential direction viathe clearance 38 may be used as a circumferential-direction reference tobe brought into contact with a circumferential-direction positioningpart of the inspection rod holder 520.

Embodiments of the present invention were described in detail above, butthe present invention is not limited thereto, and various amendments andmodifications may be implemented.

For instance, although the seal plate assemblies 42(42A to 42K, M) havebeen described in conjunction with the case where the seal plateassembly 42 is disposed on the downstream side of the rotor disc 18 inthe axial direction, the seal plate assembly may be disposed on theupstream side of the rotor disc in the axial direction.

That is, the seal plate assembly includes a seal plate disposed on afirst side of the rotor disc in the axial direction of the rotor disc,and a seal plate restraint part for restricting movement of the sealplate relative to the rotor disc in the radial direction of the rotordisc. The method for disassembling/assembling a gas turbine includes aseal-plate-restraint-state switching step of moving the seal platerestraint part along the axial direction to switch between the sealplate non-restraint state where the seal plate restraint part does notrestrict movement of the seal plate in the radial direction and the sealplate restraint state where at least a part of the seal plate restraintpart protrudes in the axial direction from the seal plate and therebyrestricts movement of the seal plate in the radial direction.

Thus, since the seal plate non-restraint state and the seal platerestraint state are switched by moving the seal plate restraint partalong the axial direction in the seal-plate-restraint-state switchingstep, for instance, even if force acts on the seal plate restraint partin a direction different from the axial direction of the seal platerestraint part by friction caused between the outer peripheral surfaceof the rotor disc and the seal plate restraint part due to vibrationduring operation of the gas turbine, or due to acceleration ordeceleration of rotation of the rotor disc during operation of the gasturbine, the seal plate non-restraint state and the seal plate restraintstate are not easily switched. Thus, it is possible to control switchingbetween the engagement state and the non-engagement state between theseal plate and the blade at an unintended timing.

REFERENCE SIGNS LIST

-   2 Gas turbine-   4 Compressor-   6 Combustor-   8 Turbine-   10 Turbine casing-   12 Vane row-   14 Blade row-   16 Gas turbine rotor-   18 Rotor disc-   20 Vane-   22 Blade-   24 Outer peripheral surface-   26 Blade groove-   28 Blade body-   30 Platform-   32 Shank-   34 Blade root-   36 Outer groove-   38 Clearance-   40 Inner groove-   42 Seal plate assembly-   44, 110 Seal plate-   45 Plug-   46 Seal plate restraint part-   48, 120 Radially outer end portion-   50 First surface-   52 Second surface-   54, 102, 118, 134, 194, 196 End surface-   56 Locking plate-   58 Locking piece-   60 Plate body part-   62 Rising part-   63 Edge-   64, 124 Radially inner end portion-   66 Lap part-   68 Plate-   70 Pressing screw-   72, 112 Plate part-   74 Accommodation chamber-   76 Accommodation chamber forming part-   78 Opening-   80 Wall part-   82 Cylindrical part-   84, 142, 156, 184 Female thread-   85 Cylindrical member-   86 Thread-   86 Male thread-   86, 144, 158, 186 Male thread-   88 Brim part-   90 Protruding part-   92 Jig engagement portion-   94 Biasing part-   95 Body part-   96 Brim restraint part-   97 Branch part-   98, 118, 162 Stepped portion-   100 Projection-   104, 116 Thinned portion-   105, 126 Portion-   108 Jig engagement recess-   114, 152 Projecting part-   122 Projection-   128 Region-   130 Nord-Lock washer-   132 Strut-   136 Compression restriction part-   138 Facing part-   140, 154, 160 178 Through hole-   146 Washer-   148 Receiving part-   150 Recess-   164 Fall prevention pin cap-   166 Thickened portion-   168 Pin groove part-   170 Retaining portion-   180 Seal plate fall prevention piece-   182 Seal plate fall prevention pin-   192 Support part-   193 Annular spacer-   500 Inspection device-   510 Inspection rod-   512 Proximal end portion-   514 (514A, 514B) Measurement surface-   516 Distal end portion-   518 Enlarged diameter part-   520 Inspection rod holder-   522 Holding hole-   522A Enlarged diameter portion-   524 Axial-direction positioning surface-   526 Radial-direction positioning surface-   528 Measurement reference surface-   600 Axial-direction reference surface-   610 Radial-direction reference surface

1-40. (canceled)
 41. A method for disassembling/assembling a gasturbine, the gas turbine including a seal plate disposed on a first sideof a rotor disc in an axial direction of the rotor disc, and a sealplate restraint part for restricting movement of the seal plate relativeto the rotor disc in a radial direction of the rotor disc, the methodcomprising a seal-plate-restraint-state switching step of moving theseal plate restraint part along the axial direction to switch between aseal plate non-restraint state where the seal plate restraint part doesnot restrict movement of the seal plate in the radial direction and aseal plate restraint state where at least a part of the seal platerestraint part protrudes in the axial direction from the seal plate andthereby restricts movement of the seal plate in the radial direction.42. The method for disassembling/assembling a gas turbine according toclaim 41, wherein the first side in the axial direction is a downstreamside of a combustion gas flow in the axial direction, and a second sidein the axial direction is an upstream side of the combustion gas flow inthe axial direction.
 43. The method for disassembling/assembling a gasturbine according to claim 41, wherein the seal-plate-restraint-stateswitching step includes operating the seal plate restraint part througha space between two adjacent blades, on a radially inner side ofplatforms of the two blades, to switch between the seal platenon-restraint state and the seal plate restraint state.
 44. The methodfor disassembling/assembling a gas turbine according to claim 41,wherein the rotor disc includes a through hole extending along the axialdirection, and wherein the seal-plate-restraint-state switching stepincludes operating the seal plate restraint part via the through hole toswitch between the seal plate non-restraint state and the seal platerestraint state.
 45. The method for disassembling/assembling a gasturbine according to claim 41, wherein the seal-plate-restraint-stateswitching step includes switching between a state where the seal platerestraint part does not engage with the rotor disc and a state where theseal plate restraint part engages with the rotor disc by moving the sealplate restraint part along the axial direction to switch between theseal plate non-restraint state and the seal plate restraint state. 46.The method for disassembling/assembling a gas turbine according to claim41, wherein the seal-plate-restraint-state switching step includesmoving the seal plate restraint part between a position where the sealplate restraint part and the rotor disc do not overlap in the axialdirection and a position where the seal plate restraint part and therotor disc overlap in the axial direction to switch between the sealplate non-restraint state and the seal plate restraint state.
 47. Themethod for disassembling/assembling a gas turbine according to claim 41,wherein the seal-plate-restraint-state switching step includes rotatingthe seal plate restraint part while one of a female thread or a malethread provided in the seal plate restraint part is screwed with theother of the female thread or the male thread provided in the seal plateto switch between the seal plate non-restraint state and the seal platerestraint state.
 48. The method for disassembling/assembling a gasturbine according to claim 47, wherein the seal-plate-restraint-stateswitching step includes moving the seal plate restraint part along theaxial direction against a biasing force of a biasing part biasing theseal plate restraint part to switch from the seal plate restraint stateto the seal plate non-restraint state.
 49. The method fordisassembling/assembling a gas turbine according to claim 41, whereinthe seal-plate-restraint-state switching step includes switching betweena state where the seal plate restraint part does not engage with theseal plate and a state where the seal plate restraint part engages withthe seal plate to switch between the seal plate non-restraint state andthe seal plate restraint state.
 50. The method fordisassembling/assembling a gas turbine according to claim 49, whereinthe seal plate restraint part is a seal plate fall prevention pinextending along the axial direction, and wherein theseal-plate-restraint-state switching step includes switching between astate where a leading end of the seal plate fall prevention pin does notengage with a recess formed in the seal plate and a state where theleading end of the seal plate fall prevention pin engages with therecess formed in the seal plate to switch between the seal platenon-restraint state and the seal plate restraint state.
 51. The methodfor disassembling/assembling a gas turbine according to claim 49,wherein the seal plate restraint part is a seal plate fall preventionpiece, and wherein the seal-plate-restraint-state switching stepincludes removing the seal plate fall prevention piece mounted in arecess formed in the seal plate from the recess, or mounting the sealplate fall prevention piece in the recess, to switch between the sealplate non-restraint state and the seal plate restraint state.
 52. Themethod for disassembling/assembling a gas turbine according to claim 41,wherein the seal plate and the seal plate restraint part are formedintegrally, and wherein the seal-plate-restraint-state switching stepincludes plastically deforming the seal plate restraint part to switchbetween the seal plate non-restraint state and the seal plate restraintstate.
 53. The method for disassembling/assembling a gas turbineaccording to claim 41, wherein the seal-plate-restraint-state switchingstep includes rotating the seal plate restraint part while a male threadprovided in the seal plate restraint part is screwed with a femalethread provided in a through hole penetrating the seal plate to switchbetween the seal plate non-restraint state and the seal plate restraintstate.
 54. The method for disassembling/assembling a gas turbineaccording to claim 41, wherein a jig engagement recess or a jigengagement protrusion capable of engaging with a jig is formed in asurface of the seal plate which faces toward a second side in the axialdirection, and wherein the method comprises moving the seal plate in theradial direction while the jig engagement recess or the jig engagementprotrusion engages with the jig to switch between a blade non-restraintstate where the seal plate does not restrict movement of a blade alongthe axial direction and a blade restraint state where the seal platerestricts movement of the blade along the axial direction.
 55. Themethod for disassembling/assembling a gas turbine according to claim 41,wherein the gas turbine includes a plurality of seal plate assembliesincluding the seal plate and the seal plate restraint part, wherein theplurality of seal plate assemblies includes a pair of seal plateassemblies which are adjacent to each other in a circumferentialdirection of the rotor disc, and wherein the method further comprises astep of removing a pair of blades corresponding to the pair of sealplate assemblies from the rotor disc, moving other seal plates atdifferent positions from the pair of seal plate assemblies in thecircumferential direction through a space caused by removing the pair ofblades, and removing the other seal plates.
 56. The method fordisassembling/assembling a gas turbine according to claim 41, whereinthe seal-plate-restraint-state switching step includes switching theseal plate non-restraint state and the seal plate restraint state whilethe rotor disc is covered on an outer side in the radial direction. 57.A seal plate assembly for a blade of a gas turbine, comprising: a sealplate having a first surface and a second surface which face in oppositedirections; and a movable part capable of protruding from the firstsurface at a variable protrusion amount.
 58. The seal plate assemblyaccording to claim 57, wherein the seal plate has one of a female threador a male thread extending along a direction perpendicular to the firstsurface, and wherein the movable part has the other of the female threador the male thread which is screwed with the one of the female thread orthe male thread.
 59. The seal plate assembly according to claim 57,further comprising a biasing part biasing the movable part in adirection in which the movable part protrudes from the first surface,wherein the seal plate has one of a female thread or a male threadextending along a direction perpendicular to the first surface, and themovable part has the other of the female thread or the male thread whichis screwed with the one of the female thread or the male thread.
 60. Theseal plate assembly according to claim 59, wherein the biasing partincludes a disc spring or a coil spring.
 61. The seal plate assemblyaccording to claim 57, wherein the seal plate includes a plate part andan accommodation chamber forming part forming an accommodation chamberfor accommodating the movable part, and wherein the movable part isconfigured so that at least a part of the movable part is capable ofprotruding from an opening formed in the first surface of theaccommodation chamber forming part.
 62. The seal plate assemblyaccording to claim 61, wherein the accommodation chamber forming partprotrudes from the plate part in a direction in which the second surfacefaces.
 63. The seal plate assembly according to claim 62, wherein theaccommodation chamber forming part protrudes from the plate part in thedirection in which the second surface faces in both a range where themovable part exists in a width direction of the seal plate and a rangewhere the movable part does not exist in the width direction.
 64. Theseal plate assembly according to claim 62, wherein the accommodationchamber forming part protrudes from the plate part in the direction inwhich the second surface faces over a range of 80% or more of a lengthof the seal plate in a width direction of the seal plate.
 65. The sealplate assembly according to claim 61, wherein the accommodation chamberforming part has a thinned portion at a different position from theaccommodation chamber.
 66. The seal plate assembly according to claim57, wherein the movable part is disposed away from a center of the sealplate in a width direction of the seal plate.
 67. The seal plateassembly according to claim 66, wherein the seal plate has a projectionprotruding from an edge of the seal plate extending in the widthdirection, and the projection is located across the center of the sealplate in the width direction from the movable part.
 68. A gas turbinerotor comprising: a rotor disc; a plurality of blades mounted on therotor disc; and at least one seal plate assembly for the blades, whereinthe at least one seal plate assembly includes the seal plate assemblyaccording to claim
 57. 69. The gas turbine rotor according to claim 68,further comprising: a locking plate for holding the seal plate betweenthe locking plate and an end surface of the rotor disc; and a lockingpiece configured to press the locking plate toward the end surface ofthe rotor disc.
 70. A gas turbine rotor comprising: a rotor disc; aplurality of blades mounted on the rotor disc; and at least one sealplate assembly for the blades, wherein the at least one seal plateassembly includes a pair of seal plate assemblies which are adjacent toeach other in a circumferential direction of the rotor disc, and whereineach of the pair of seal plate assemblies is the seal plate assemblyaccording to claim
 57. 71. A gas turbine rotor comprising: a rotor disc;a plurality of blades mounted on the rotor disc; at least one seal plateassembly for the blades, and another seal plate not provided with amovable part, wherein the at least one seal plate assembly includes aplurality of seal plate assemblies arranged symmetrically around arotation center of the rotor disc, and wherein each of the plurality ofseal plate assemblies arranged symmetrically is the seal plate assemblyaccording to claim
 57. 72. A gas turbine rotor comprising: a rotor disc;a plurality of blades mounted on the rotor disc; and the seal plateassembly according to claim 57, wherein the seal plate includes a platepart and an accommodation chamber forming part forming an accommodationchamber for accommodating the movable part, wherein the accommodationchamber forming part protrudes from the plate part in a direction inwhich the second surface faces, wherein the gas turbine rotor furthercomprises a seal plate not provided with the movable part, and whereinthe seal plate not provided with the movable part includes a plate partand a projecting part protruding from the plate part in a direction inwhich the second surface faces.
 73. A gas turbine rotor comprising: arotor disc; a plurality of blades mounted on the rotor disc; and theseal plate assembly according to claim 57, wherein the seal plateincludes a plate part and an accommodation chamber forming part formingan accommodation chamber for accommodating the movable part, wherein theaccommodation chamber forming part protrudes from the plate part in adirection in which the second surface faces, wherein the accommodationchamber forming part has a first thinned portion at a position differentfrom the accommodation chamber, wherein the gas turbine rotor furthercomprises another seal plate not provided with the movable part, whereinthe another seal plate includes a plate part and a projecting partprotruding from the plate part in a direction in which the secondsurface faces, and wherein the projecting part has a second thinnedportion having a different dimension from the first thinned portion. 74.A gas turbine comprising: the gas turbine rotor according to claim 68;and a casing covering the gas turbine rotor.
 75. A method for producinga gas turbine, the gas turbine including a seal plate disposed on afirst side of a rotor disc in an axial direction of the rotor disc, anda seal plate restraint part for restricting movement of the seal platerelative to the rotor disc in a radial direction of the rotor disc, themethod comprising a seal-plate-restraint-state switching step of movingthe seal plate restraint part along the axial direction to switch from aseal plate non-restraint state where the seal plate restraint part doesnot restrict movement of the seal plate in the radial direction to aseal plate restraint state where at least a part of the seal platerestraint part protrudes in the axial direction from the seal plate andthereby restricts movement of the seal plate in the radial direction.